They are located in:
https://www.ubbcentral.com/forums/ubbthreads.php/forums/17/1/language-packs

Bear in mind they are created and contributed by users.

So many of them may be out of date and need work for a current ubb version.

BTW,
Language packs my not work the way you think.
A member can't elect a different language pack to use other than the default used by the board.

Blue Man Group
There is no such thing as stupid questions. Just stupid answers