This is a good question - which unfortunately I don't have an answer, but I working on a similar problem with a tune right now...

Real Drums (RD) are my go-to drums simply because they do so much and sound so fine so fast. If you are not a drummer then RD's are the best as you just select one and your done. But... when you really need that single sound, in your case "HiHats Only" or in my case "brushes on 2 and 4 only" they just don't have the flexibility to get what you want. I guess it is the same for all the BIAB RTs, but drums seem to be a special case as other RTs can be close to what you want and still work, but if the drums are off then there is a big part missing.

For me, I am about to move over to Jamstix in my DAW and see if I can get my sounds. I would prefer not to move out of BIAB just yet with this song but the drums just need to be better now.

So at this point I think all we can do is go to the wishlist forum and ask for is more "edit ability" for the RDs in future versions.

BIAB – 2025, Reaper (current), i7-12700F Processor, 32GB DDR4-3200MHz RAM, 1TB WD Black NVMe SSD, 2TB WDC Blue SSD, 1TB WD Blue, 2 TB SK NVMe, 6 TB External, Motu Audio Express 6x6