Hey,
Bah, would you mind walking through how you got everything working on Arch? I got the game installed, with the GOG installer, and it works but there is no sound. Tried the Linux guide in the wiki, but I keep getting errors when installing directmusic and gmdls. The wiki is pretty old, so I'm skeptical to believe it still works.
I'm actually using the Steam version and proton, so I didn't have to manually create a wineprefix, since proton did that for me. Using protontricks, all I needed to run was "protontricks <gameid> gmdls directmusic". The order listed there was important because directmusic gets an error at quartz.dll and bombs out, and if gmdls was listed 2nd then it wouldn't actually install. So in a manual wine-prefix, I would try installing them separately:
winetricks gmdls
winetricks directmusic
If the directmusic install fails at quartz.dll then you got as far as I did, and music should play.
The only other thing I should note is that when I installed grimoire with proton I was using wine 3.16. I've since updated to wine 4.11 and it still plays, but it's possible that the older version of wine helped with getting gmdls and directmusic installed.