Seems like proton-5.13 runs the game :-) I've only played 4-5 levels thus far, but no issues at all - sound, music, animations, UI, everything is working perfectly. I'm not sure what to do, so I'll just leave this ticket...
I've verified the game files and I've tried several different version of wine, including 5.19, 5.18, proton-5.0-9 (steams), 4.11, and 5.9. I deleted the compatdata pfx between tries. I've also tried deleting the `libmpg1...