Multilanguage files and library division

[TheDreadPirate]

This is purely your preference. In my setup I separate content based on country of origin. If that is what you're doing now, I'd continue to do that regardless of what audio/subtitle tracks they have.

If you're separating the same show based on just the audio tracks available, that is sub-optimal, IMO. Double the storage. If these are the same shows with different audio tracks, I would opt to remux the audio into one file and remove the "default" tag so their audio preference is used.