A point of translation nuance here: in American English “one does not speak {language} here” carries with it an overt sense of pretense or unpleasantness, whereas in French “on”/one is very commonly used as an alternative to “we” in informal conversation, and does not carry any of the same tone as using “one” does in English. While the translation is correct at a literal level, idiomatically it’d just be “we don’t speak English here”.