The bilingual ref??

Should it be mandatory? Yes or no

Do you mean should the refs in the USA speak both foreign European languages of English from England and Spanish from Spain? ;)

I don't think it should be mandatory, it certainly wouldn't hurt though.
The referees seem to get along very well with the sign language that has developed over the years, in my opinion.
Somebody will probably straighten me out but I can't recall a huge problem that language caused during a fight.

The visions of jay nady shaking his finger at Tito Trinidad come to mind. Trinidad had no explanation just a finger wag like you would give to a toddler. I like Tony weeks. He's bilingual and gives commands and instructions in both languages. Obviously it would be difficult to find a ref who speaks Ukrainian ( I think they have the own) or an Asian language.