My music library includes files with Funky Unicode Names and I have no idea if it's Android, KDE/Dolphin, or the SD card but it regularly eats entire albums and doesn't show them in the media library nor file browsers even though the files exist.
I mention KDE because as far as I remember this didn't happen on Windows. I'll have to try and copy them via MTP on it. MTP transfers of these cursed files always fail on Dolphin.
Although, last night before bed I was reading up on the exFAT spec and I seem to remember reading up on how filename management is sort of up to the implementation? It could be that the filesystem handling baked in-house at Oppo just sucks.