There is a clear distinction between the time sig that music is PLAYED in vs. the time sig that it is NOTATED in. This has been true, literally since the Middle Ages (more on that below).
So if a style is played in 12/8, it can either be notated in 4/4 or 12/8, and this is a standard convention, not something that BiaB thought up.
For example, traditional jazz music is written in 4/4 but played in 12/8. Such music may be annotated "with a swing" or similar, but the swing also may be assumed. The last sentence in bold is a direct quote from Wikipedia, and illustrates my point.
https://en.m.wikipedia.org/wiki/Swing_(jazz_performance_style) Any music that is played in a triplet feel (3 divisions per note), is considered compound time. This is found in all BiaB styles that are jazz swing, shuffle, irish jig, or any style with a triplet (compound, 12/8) feel. There are about 1,300 BiaB styles like this that are played in 12/8, but notated in 4/4. For any triplet feel 4/4 style, the composer can notate it in 12/8 or 4/4 as a personal choice. For example, jazz swing music would be a candidate to be wriitten in 12/8, since it is a compound (triplet) feel style. Instead, the notation gets a marking at the beginning that (8th notes get played as triplets, with the first one twice as LONG and the second one SHORT). Irish jigs have the same feel as jazz swing, but since the melodies have more triplets, (and it is the melody that gets notated), the tradition is that this gets notated in 12/8 for Irish jigs. But this has nothing to do with how they are played. It is more like a decision to use double spacing vs single spacing for a speech you're writing out (it will sound the same when read out loud).
The idea of using a 4/4 time signature to display a triplet feel 4/4 style, instead of using 12/8 has been going on since the Middle Ages. This is called "Notes inégales". Most of the time it refers to playing two 8th notes in a triplet feel, with the first one LONG and the second one SHORT. And this convention allows the music to be written in 4/4 instead of 12/8, This started with early noation of Gregorian chants, and then baroque music.
and it reappeared as the standard performance practice in the 20th century in jazz. The last sentence in bold is a direct quote from Wikipedia, and you can read about it
https://en.m.wikipedia.org/wiki/Notes_in%C3%A9gales Anyway, the point for BiaB is, there is no requirement to notate triplet feels in 12/8, and considering a Irish Jig to be in 4/4 ((instead of 6/8) is no harder than considering a jazz tune like Alexander's Rag Time Band to be in 4/4 (instead of 12/8).
So, in repsonse to the original poster. There are 1,320 styles in Band-in-a-Box that are triplet feel eighth note styles, which make then 12/8 playing styles. And there are 93 styles that have guitar and have also been marked by us as 12/8 (see those below)
It really depends how "triplet-y" you want, and if you're looking for some really triplet-y ones, you could use the text filter and type in 12/8 guitar . If you do that, here's a list of 93 of the 1,320 Swing 8ths styles that have been flagged to work well with 12/8 and all have guitar. I've included links to the demos, so you can listen for yourself.
93 12/8 guitar styles , that are found using a text filter of 12/8 guitar in stylepicker for BiaB 2016
Name Long Name Tempo Demo URL
RealStyles (all RealInstruments, no MIDI)
_128P50S 50's 12/8 Pop 85
http://demos.pgmusic.com/audio/allstyledemos2/_128P50S.m4a_SPOP128 12/8 Soul Pop 85
http://demos.pgmusic.com/audio/allstyledemos2/_SPOP128.m4a_SPTRIO1 12/8 Soul Pop Trio 85
http://demos.pgmusic.com/audio/allstyledemos2/_SPTRIO1.m4a_TBLZBSS Slow 12/8 Bari Sax Solo Blues 60
http://demos.pgmusic.com/audio/allstyledemos2/_TBLZBSS.m4a_TBLZSEV Slow 12/8 Blues w/ Vintage Piano 85
http://demos.pgmusic.com/audio/allstyledemos2/_TBLZSEV.m4a_BLZ12PA Bluesy Acoustic Piano 12/8 w/ Band 60
http://demos.pgmusic.com/audio/allstyledemos2/_BLZ12PA.m4a_MANS128 Mandolin Solo 12/8 Country Swing 65
http://demos.pgmusic.com/audio/allstyledemos2/_MANS128.m4a_BMCS128 Country 12/8 Piano w/ Guitar Solo 65
http://demos.pgmusic.com/audio/allstyledemos2/_BMCS128.m4a_RESS128 Resonator Solo & Piano 12/8 65
http://demos.pgmusic.com/audio/allstyledemos2/_RESS128.m4a_PNOC128 Acoustic Piano 12/8 Country 65
http://demos.pgmusic.com/audio/allstyledemos2/_PNOC128.m4a_GUITBLZ Country Blues 65
http://demos.pgmusic.com/audio/allstyledemos2/_GUITBLZ.m4a_BLZ_MNH Laid Back Blues 65
http://demos.pgmusic.com/audio/allstyledemos2/_BLZ_MNH.m4a_TBLZSLT Texas Blues 12/8 w/ Trading Solos 60
http://demos.pgmusic.com/audio/allstyledemos2/_TBLZSLT.m4a_TBLZSLS Texas Blues 12/8 w/ Guitar Solo 60
http://demos.pgmusic.com/audio/allstyledemos2/_TBLZSLS.m4a_TBLZSLR Texas Blues 12/8 60
http://demos.pgmusic.com/audio/allstyledemos2/_TBLZSLR.m4a_TBLZSLP Texas Blues 12/8 w/ Piano Solo 60
http://demos.pgmusic.com/audio/allstyledemos2/_TBLZSLP.m4a_TBLZSLB Texas Blues 12/8 w/ Brent 60
http://demos.pgmusic.com/audio/allstyledemos2/_TBLZSLB.m4a_TBLRKSL Blues Rock 12/8 w/ Alto Solo 60
http://demos.pgmusic.com/audio/allstyledemos2/_TBLRKSL.m4a_CMPFBHF Campfire, Hank Fingerpicked 65
http://demos.pgmusic.com/audio/allstyledemos2/_CMPFBHF.m4a_CMPFBH3 Campfire, Hank w/ Bass 65
http://demos.pgmusic.com/audio/allstyledemos2/_CMPFBH3.m4a_CMPFBH2 Campfire, Hank 65
http://demos.pgmusic.com/audio/allstyledemos2/_CMPFBH2.m4a_MONDOR Slow Swing Blues w/ Organ 65
http://demos.pgmusic.com/audio/allstyledemos2/_MONDOR.m4a_CJIGBZK Celtic Jig w/ Band 110
http://demos.pgmusic.com/audio/allstyledemos2/_CJIGBZK.m4a_FPBTACS Acoustic Folk w/ 2 Fingerpicked Guitars 65
http://demos.pgmusic.com/audio/allstyledemos2/_FPBTACS.m4a_FPBNTSS Slow Swing Country w/ 2 Fingerpicked Guitars 65
http://demos.pgmusic.com/audio/allstyledemos2/_FPBNTSS.m4a_PSSO128 12/8 Country Ballad w/ Pedal Steel Solo 65
http://demos.pgmusic.com/audio/allstyledemos2/_PSSO128.m4a_P128PNS Slow Pop 12/8 w/ Piano Solo 65
http://demos.pgmusic.com/audio/allstyledemos2/_P128PNS.m4a_C128PNS Slow Country 12/8 w/ Piano Solo 65
http://demos.pgmusic.com/audio/allstyledemos2/_C128PNS.m4a_CT128BR Country 12/8 Brent Electric Guitar Solo 65
http://demos.pgmusic.com/audio/allstyledemos2/_CT128BR.m4a_POPPNOS Pop Piano 12/8 Ballad 65
http://demos.pgmusic.com/audio/allstyledemos2/_POPPNOS.m4a_MONDAY Slow Swing 8ths Blues 65
http://demos.pgmusic.com/audio/allstyledemos2/_MONDAY.m4a_CRYSTAL Country 12/8 Ballad w/ Pedal Steel 65
http://demos.pgmusic.com/audio/allstyledemos2/_CRYSTAL.m4a_ElBlz1 [RT n/a] Slow Electric Blues 65
http://demos.pgmusic.com/audio/allstyledemos2/_ElBlz1.m4a_AcBlz2 [RT n/a] Slow Blues 65
http://demos.pgmusic.com/audio/allstyledemos2/_AcBlz2.m4a_AcBlz1 Sparse Blues 65
http://demos.pgmusic.com/audio/allstyledemos2/_AcBlz1.m4a_SLOBLZ1 Slow and Gritty Blues 65
http://demos.pgmusic.com/audio/allstyledemos2/_SLOBLZ1.m4aStyles with Some MIDI in them
M_S128BL Slow 12/8 Blues MIDI Piano 85
http://demos.pgmusic.com/audio/allstyledemos2/M_S128BL.m4aM_BLZ128 Slow 12/8 Bluesy Band w/ Piano 60
http://demos.pgmusic.com/audio/allstyledemos2/M_BLZ128.m4aM_PNC128 12/8 Country w/ MIDI Piano 65
http://demos.pgmusic.com/audio/allstyledemos2/M_PNC128.m4aM_TBLSLP Solo Texas Blues Rock 12/8 MIDI 60
http://demos.pgmusic.com/audio/allstyledemos2/M_TBLSLP.m4aM_C128PN Slow Country 12/8 w/ Piano Solo 65
http://demos.pgmusic.com/audio/allstyledemos2/M_C128PN.m4aStyles with Some/All MIDI in them
=AG_BESS Blues Gospel w/ Organ 62
http://demos.pgmusic.com/audio/allstyledemos2/=AG_BESS.m4a=PED128B Slow Country Ballad 65
http://demos.pgmusic.com/audio/allstyledemos2/=PED128B.m4a=CR128_B 12/8 Country Ballad 65
http://demos.pgmusic.com/audio/allstyledemos2/=CR128_B.m4a=BGPOP_B Country Swing Ballad 85
http://demos.pgmusic.com/audio/allstyledemos2/=BGPOP_B.m4a=SWBA_TB Soul Ballad w/ Trombone 85
http://demos.pgmusic.com/audio/allstyledemos2/=SWBA_TB.m4a=FLK12_T Blues 12/8 w/ Trumpet 75
http://demos.pgmusic.com/audio/allstyledemos2/=FLK12_T.m4a=CAR_BAS Carey 12/8 w/ Alto Sax 70
http://demos.pgmusic.com/audio/allstyledemos2/=CAR_BAS.m4a=LA_PB_B LA Pop Ballad w/ Acoustic Bass 90
http://demos.pgmusic.com/audio/allstyledemos2/=LA_PB_B.m4a=CNT_OTB Old Country w/ Trombone 130
http://demos.pgmusic.com/audio/allstyledemos2/=CNT_OTB.m4aAG_BESS AG_BESS - Bluesy 12/8 Gospel 62
http://demos.pgmusic.com/audio/allstyledemos2/AG_BESS.m4aTEXASBL Texas Blues - 12/8 Slow Blues 55
http://demos.pgmusic.com/audio/allstyledemos2/TEXASBL.m4a-CS128^4 Country Shuffle 128 62 http://demos.pgmusic.com/audio/allstyledemos2/-CS128^4.m4a
-CS128^5 Country Shuffle 128 62 http://demos.pgmusic.com/audio/allstyledemos2/-CS128^5.m4a
-CS128^6 Country Shuffle 128 62 http://demos.pgmusic.com/audio/allstyledemos2/-CS128^6.m4a
NR_NORJ+ NORJ 12/8 Nashville Rock + 65
http://demos.pgmusic.com/audio/allstyledemos2/NR_NORJ+.m4aBuddyG BuddyG - Raucous 12/8 Blues 95
http://demos.pgmusic.com/audio/allstyledemos2/BuddyG.m4a-CS128^2 Country Shuffle 128 70 http://demos.pgmusic.com/audio/allstyledemos2/-CS128^2.m4a
-CS128^1 Country Shuffle 128 70 http://demos.pgmusic.com/audio/allstyledemos2/-CS128^1.m4a
-CLTJG^2 Celtic Jig 125 http://demos.pgmusic.com/audio/allstyledemos2/-CLTJG^2.m4a
-CLTJG^1 Celtic Jig 125 http://demos.pgmusic.com/audio/allstyledemos2/-CLTJG^1.m4a
-CLTJG^4 Celtic Jig 120 http://demos.pgmusic.com/audio/allstyledemos2/-CLTJG^4.m4a
-PO128^7 Pop128-7-Brushes Style 80 http://demos.pgmusic.com/audio/allstyledemos2/-PO128^7.m4a
-PO128^6 Pop128-6-SideStick, Snare Style 80 http://demos.pgmusic.com/audio/allstyledemos2/-PO128^6.m4a
-PO128^5 Pop128-5-Brushes, Snare Style 80 http://demos.pgmusic.com/audio/allstyledemos2/-PO128^5.m4a
-PO128^4 Pop128-4-Brushes, SideStick Style 80 http://demos.pgmusic.com/audio/allstyledemos2/-PO128^4.m4a
-PO128^3 Pop128-3-Brushes, Ride Style 80 http://demos.pgmusic.com/audio/allstyledemos2/-PO128^3.m4a
-PO128^2 Pop128-2-Snare, Ride Style 80 http://demos.pgmusic.com/audio/allstyledemos2/-PO128^2.m4a
-PO128^1 Pop128-1-SideStick, Ride Style 80 http://demos.pgmusic.com/audio/allstyledemos2/-PO128^1.m4a
BEEBSLO BeeB Slow - Slow 12/8 Blues 65
http://demos.pgmusic.com/audio/allstyledemos2/BEEBSLO.m4aIslands Islands - Slow 12/8 60's Pop 70
http://demos.pgmusic.com/audio/allstyledemos2/Islands.m4aPsyk128 Psyk 12/8 - Slow 12/8 Pop/Rock 50
http://demos.pgmusic.com/audio/allstyledemos2/Psyk128.m4a-PERCY~ Percy-Slow 12/8 50s Pop 65 http://demos.pgmusic.com/audio/allstyledemos2/-PERCY~.m4a
-MudySlo Mudy Slow Slow Blues 65
http://demos.pgmusic.com/audio/allstyledemos2/-MudySlo.m4a-C_CONWY Conway-Classic 50s 12/8 Country 80
http://demos.pgmusic.com/audio/allstyledemos2/-C_CONWY.m4aOreg1 Oreg 1 - 12/8 Ambient World Beat 105
http://demos.pgmusic.com/audio/allstyledemos2/Oreg1.m4aGloria Gloria - Brit 80s Rock Shuffle 110
http://demos.pgmusic.com/audio/allstyledemos2/Gloria.m4a12_8Surf 12/8 Surf - Slow 12/8 - 60s Pop 70
http://demos.pgmusic.com/audio/allstyledemos2/12_8Surf.m4aFOLK12_8 Folk 12/8 - 60s Folk Groups 75
http://demos.pgmusic.com/audio/allstyledemos2/FOLK12_8.m4aTarentla Tarentella - World Styles - Italy 140
http://demos.pgmusic.com/audio/allstyledemos2/Tarentla.m4a128Rok1 12/8 Power Rock Ballad 70
http://demos.pgmusic.com/audio/allstyledemos2/128Rok1.m4a128Rok2 12/8 Loud Rock Feel 65
http://demos.pgmusic.com/audio/allstyledemos2/128Rok2.m4aPADDY Paddy - Celtic Jig - World Styles 120
http://demos.pgmusic.com/audio/allstyledemos2/PADDY.m4aCelt_JIG Celtic Jig Style - World Styles 120
http://demos.pgmusic.com/audio/allstyledemos2/Celt_JIG.m4aC_CONWAY Conway - Classic 50s 12/8 Country 80
http://demos.pgmusic.com/audio/allstyledemos2/C_CONWAY.m4aJ!SATCH Vintage Jazz - Satch Slow 12/8 Pop 80 http://demos.pgmusic.com/audio/allstyledemos2/J!SATCH.m4a
PERCY!~ Percy - Slow 12/8 50s Pop 65 http://demos.pgmusic.com/audio/allstyledemos2/PERCY!~.m4a
CAREY128 Carey 12/8 - Top 40 12/8 70
http://demos.pgmusic.com/audio/allstyledemos2/CAREY128.m4aCELTIC2 Celtic 2 - Contemporary Celtic 125
http://demos.pgmusic.com/audio/allstyledemos2/CELTIC2.m4aCELTIC1 Celtic 1 - Contemporary Celtic 125
http://demos.pgmusic.com/audio/allstyledemos2/CELTIC1.m4aKILARNEY Irish-Shotiche 12/8 Style 110
http://demos.pgmusic.com/audio/allstyledemos2/KILARNEY.m4aZ4COUN12 Country 12/8 Feel 120
http://demos.pgmusic.com/audio/allstyledemos2/Z4COUN12.m4aREGGAE_2 Reggae 2 165
http://demos.pgmusic.com/audio/allstyledemos2/REGGAE_2.m4a 
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