Yeah.. E-Tube Project V4 can re-flash the firmware and will work with the SM-BCR2 charger. V3.4.5 can also update firmware

.
(if ETP V4 complains that the SM-BCR2 firmware is 'old', run ETP 3.4.5 and it'll update the BCR2 firmware for you)
https://bike.shimano.com/en-EU/e-tub...t/archive.html
FD-R9150 should trim, yeah... Did it stop trimming before or after you changed the limit settings?
I think I would also reset all limits and set them up from scratch, and see what that does.