I've come to the conclusion this will never happen so I've given up on it. I love BIAB but it's just so unbearable to use. The only good (and necessary) thing that's happened in the last couple of years is partial regeneration, but this is still implemented badly for drums and still doesn't work on midi - two things that at the very least I was hoping to see for 2025.
The new multipicker is a mess, I rarely use it and wish they would revert to the layout 2023 pickers. Too many things never get addressed. With DAW chord tracks, Toontrack, Ujam etc - I think BIAB is getting closer to having had its day and slowly dropping off the radar.