Thank you for the suggestions! I'll give it another go, see if I can make it work 👍
I was using Symfonium as my client on Android, maybe that was part of the problem.
I used Beets for processing/tagging, which was also troublesome; never could get it to do anything on its own, had to manually initiate every session, and lots of stuff needed handholding to get tagged correctly. Never could get Picard to work at all, neither in Docker nor on my desktop.