Someone asked earlier what they do in Belgium. I can tell you. All manuals etc were in English. Certainly, all of our pilots be they Flemish, French or German speaking had to be competent in English. Everyone else in the company had to have a working knowledge of English.
Some of my friends told me that all pilots in the Belgian Air Force had to be tri-lingual. All flying matters were conducted in English. That stopped the French speakers complaining that the Dutch speakers had an advantage and vice versa!
Incidentally, I remember being told by an Indian captain that communication on the Sub Continent would be pretty difficult without English. He reckoned that there were 94 languages in the old India but all of them had English speakers.