At long last my music library is repaired. With 12.2.1, they added a tool to reset iCloud Music Library, which was the piece I was waiting on Apple Engineering to do after restoring my iTunes library (that got irrevocably destroyed) to a pre-12.2 state.
Apple has a support article for those who also got all their tracks fracked. I can confirm it works.
https://support.apple.com/en-us/HT204964
Now that I'm up and running again, I once again--for the third time--went through my list of Spotify albums and added them to my Apple Music library. There were 6 albums that were not available. What I want Apple Music to do that Spotify doesn't, is to "just work" on my devices. That includes integrating my purchased library and streaming content. Check. That also means that the experience is not buggy as all get out, like Spotify is on CarPlay. The number one problem here, is there is no shuffle option for artists aside from Siri, of course. And maybe that'll prove to be fine. What I don't want is the same experience as Spotify where I have to create playlists for each artist because I can't just go to Artist and shuffle the content that I have from My Library and the streaming catalog together.
I find so far that discovering the artists I like have new content out is a little less obvious on Apple Music. On Spotify, I get a big red number that says something is new from the artists I follow. On Apple Music, I feel like I have to comb through a large breadth of information to see if something has come out. Maybe this will take getting used to and it'll be fine too, one day.
The whole track debacle really turned me off Apple Music. But so does Spotify's inoperability on CarPlay. I'm not sure what I'll end up sticking with at the end of the 90 days. But if somehow Spotify miraculously listened to all my support emails and fixed it, then yah, I see nothing here that is so much better to make the switch. AM fine now that it's running properly. I'd subscribe in a heartbeat except I already have a service and nothing here is compelling enough to change.
P.S. Edit - I've been listening to Classical Radio on AM for a few hours and it is much better than Spotify's. Point Apple.