This is the first time I have ever heard of this bug (Or someone playing on Linux), so maybe it's Linux side.
Do the other songs that have problems also have some sort of accent in their names?
I'll look into changing the names.
It probably is just a thing where Linux doesn't like whatever formatting you did, yeah. I won't pretend I know enough about character encoding to speculate further. The game does run very well through Proton besides this one issue, though, besides this one issue obviously.
And yeah, all the songs I've seen that have errors all have accents in the name.
By the way, I would also suggest adding a prompt to save when entering the Myrefall inn on the second night - since you're booted to the title screen once you hit the end of content, you could end up losing quite a lot of progress.
Also, great game so far! <3