Indeed interesting perspectives! So many things to discuss and so little space in a thread.
I know that Schönberg and Stravinsky can bit a little bit heavy on the newcomer, that's why I recommended his early works like "Verklärte Nacht" which still is very much in the realms of tonality, but he already bends it heavily - which was befitting the question I assumed. (He was around 25 when he composed it.) But maybe I was overambitious - one never knows. Always reach for the stars. ;)
The grain of salt I'd like to give back, as I'm only a musician, not a neurologist. I didn't know that people lose perfect pitch, that's completely new to me. And just to clarify: I fully second your point, that you have to train it. Perfect pitch without training is probably no big help, but I also don't know, how one without the ability could train it and get even close to one, that could do it as long es he could think. I don't think I have it, but I can - at least on my instruments, that I practise daily - guess the played pitch relatively accurate. But I also don't think, it's a necessary skill to call a note by its name when hearing it, without any context - as long as you don't sing contemporary music, there it's an extremely big help. On the other hand relative pitch hearing I would consider extremely important, this is also what Mr. Beato recommends at the end of the video. The rest, being able to imagine a timbre for example, I would consider "visualisation"-skills that can be trained like any other skill - and should. (I relate this heavily to the way a chess master is visualising the chess board and the pieces, which feels extremely difficult, but is surprisingly easy - don't say it's easy, just easier than I thought - once you realize that it's just so hard because your brain has never done it before.)
Now I've been rambling. But you can always reach out to me via PM or on discord (I've been attending the thasauce server for a couple of days) if you'd like to discuss some points further that would blow this up too much. This is interesting stuff. ;) (Same offer to @The Vodoú Queen if you have any questions whatsover regarding what I said!) Always an open ear, especially in these times where social distancing is the rule rather than the exception. And nothing's better than a good, respectful discussion that everyone leaves a little bit wiser than he/she entered.