The Star Wars we know now is a big budget tentpole film with budgets running in the hundreds of millions. Often we forget the humble beginnings of the original trilogy.
FACT: Most of the rebel ground troops in the Hoth battle were Norwegian extras. Because they didn’t speak any English, second unit director Peter MacDonald had to “act out” what he wanted them to do, by pointing in the direction of the “enemy” (which wasn’t visible during shooting) and demonstrating the recoil motion he wanted for the blaster rifles.
I don’t know how difficult working with English speaking extras is, I can’t imagine working with extras who speak a completely different language.