Translation is duplicated among many projects, not all of which will be completed at the same rate.
Instead there is
https://hosted.weblate.org/projects/iso-codes/iso-639-3/
and
https://hosted.weblate.org/projects/iso-codes/iso-639-2/
fortunately on the same instance, which solves this problem.
Can they be used for Invidious?
Looks like they're provided as PO files which aren't compatible with what Invidious uses currently.
There's currently some work being done elsewhere that should allow them to be supported. The main challenge now is converting all existing locales to PO files, but definitely should be possible in future to use this.
Most helpful comment
Looks like they're provided as PO files which aren't compatible with what Invidious uses currently.
There's currently some work being done elsewhere that should allow them to be supported. The main challenge now is converting all existing locales to PO files, but definitely should be possible in future to use this.