[jltsiren]

Locales are often compromises that don't reflect user preferences particularly well. People speak multiple languages, and they may have different preferences for content / UI languages, date/time formats etc. And the preferences may be situational, such as native X > native English > English translation/localization > X translation/localization.

Just tag the content with the relevant languages and let the user create filters based on them. And assume that the user understands that languages don't form disjoint categories, because the content itself could be multilingual.

Besides, original audio with subtitles is usually superior to dubbed audio.