I'm not a big Celtic music fan but my guess would be that you select the style and write the music then choose the instruments (in Real Band) specific to the genre and see how it turns out.

BB/RB can do so much....and if you figure out the work arounds to where it seems to stumble, you can get even further down the road.

Who would think that with over 3000 styles in BB that there would be anything lacking.... but there is. In trying to duplicate the style for a friend's song....from the recording in a night club.... there did not seem to be a matching style that I could find.

Back to Celtic.... fiddle and acoustic guitar are the basis of this style are they not? I would think a folk style would get you there. I seem to recall seeing celtic in the style listings..... or am I wrong? If so, they already have that style....I'd need to open the DAW to see...Look under the folk category.

You can find my music at:
www.herbhartley.com
Add nothing that adds nothing to the music.
You can make excuses or you can make progress but not both.

The magic you are looking for is in the work you are avoiding.