I think Real Time Audio is hard to get right. Creating a Digital Audio Workstatio (DAW) was what inspired the creation of Zig - the creator felt that it was such a difficult problem that current languages weren't sufficient. I bet it will be less trivial for AI to clone Abelton than the Adobe suite.
There are already clones like https://github.com/storytold/soundcraft out there. No idea if they're any good, but they do exist.
I'm not so sure. I've been building a live iPad based mixer for my modular the last couple of weeks. I've been a heavy user of Live and other audio apps for years and it's been pretty trivial to put together. Been running it with tons of simultaneous tracks, effects, and complex DSP with latency compensation interfacing with my 10 in 8 out interface and haven't had a glitch the entire time.
There are many kinds of Real Time Audio.
If you just do "computer music", with no synced live instruments and external synths, it's a much easier problem, 40 ms of latency is perfectly fine, and on modern hardware it's not hard to hit that target.
Real-time audio is a concern of the operating system and drivers primarily.
Yes, it’s pretty unforgiving. Low latency and live performances leave no wiggle room - software must be low latency and highly reliable. You can’t afford to drop one in 10000 buffers.