Well, I've tried what I can think of. My only remaining thought is that it's a completely undocumented bug in the specific version of Wine, which I know you can't really help with. I started thinking it might have to do with the game files themselves when I ran across a special character that was clearly improperly rendered, but I think I can dismiss that worry safely now. I just wish I was more experienced with debugging. Regardless, using the illusionist to rename my character with a capitalized name on my Windows partition solved the main issue for now, and I can revisit this when I'm actually able to troubleshoot as effectively as I'd really like.
Thanks a bunch for all the help trying to track down what the heck is going on, though! Never would have gotten this far without that. Much appreciated for sure!