resynth Is this project still in development?
The Google Summer of Code project officially ended last month. I have not had much time since, but Dhruva has kept looking into things a bit. My plan is to add support for BBAI in the generic Bela image, but that is at least a few months down the line, because there are a few other things in the making (...surprise!). One of the main blockers on the OS/image side is that the board at the moment boots fine only roughly 50% of the times when using the 4.19 Xenomai kernel and that's some nasty debugging/development to do there. I want to push it to the Xenomai mailing list and see if they have a clue because I don't.
resynth Is the CTAG supported or just Bela?
CTAG is supported only with ALSA at the moment (also the Bela cape by the way). Once the missing piece of the Bela side (IRQ from McASP to PRU) will be in place, it will support CTAG with the Bela real-time environment, too.
resynth Is it usable system that works with the Bela IDE?
The IDE works. I think we are still sub-usable overall at the moment though, given the kernel issue.