Bug? Files with "é" are always marked as "new"

[Sir-Teatei-Moonlight]

Game: Rivals of Aether II

Issue: There are some files containing "Léon" in the name. These files have been in the game for several versions, but when I compare today's version (exact date doesn't matter) with the previous one using the "All (New)" loading mode, all the "Léon" files appear as if they are new.

Looking at the .fbkp files, I can see that while "Leon" is in there a few times (this is expected, some files are "Leon" and others are "Léon"), "Léon" does not appear at all. I suspect something is going wrong with saving the file name to the backup.