Hi!
As a French user, I've seen that unfortunately you no longer support French (among others) on the last version of unarchiver, and you were looking for some volunteers :)
I might try to do it and help you to translate it in French (and maybe in Spanish, but let's deal with the French first), but I was wondering.... how ? How could I "submit" a translation, what is the best way to do it according to your needs, ... ?
Sincerely,
Elendil.