In fiction most characters seem able to communicate with each other without any problems, even if they speak different languages, though some authors use language difficulties or attempts to speak other languages for comic effect.
For example, in Terry Pratchett’s Witches Abroad, which I’m currently re-reading for the umpteenth time, one of the witches comes up with requests like, “Openny vous, gunga din, chop-chop, pretty damn quick”, “Gooden day, big-feller mine host! Trois beers pour favour us, silver plate”, and “Garkon? Mucho vino aveck zei, grassy ass”, which nobody understands. One of the other witches just speaks more slowly and turns up the volume.
Just thought I’d share this with you.