Certain endemic grammatical traits of French are all too familiar to every translator. Among them is the very fluid and multiple use of y and en. Any attempt to retain each occurrence in a translation betrays an inexperienced (or machine) translator. Less often noticed is on, an all-purpose pronoun that is exceedingly prevalent in L’Esprit des lois with close to 7000 occurrences! We may as well concede that it is a text constructed to a substantial extent on the vary liberal and flexible use of the pronoun on.
“One” is, of course, an approximate equivalent in English. The problem is that it cannot sustain a whole discourse without appearing stilted, and when overdone, it becomes unbearable. A whole repertory of work-arounds is needed which to a purist will seem a deviation from the original. But really they are necessary if the text is to sound anything like natural.
What translators do is to find other ways — and certainly more than one is needed — to avoid excessive repetition. Since on often means “we”, the first-person plural is a more than acceptable substitute. Sometimes we can say “a person” instead of on, or even “people” when, as on often does, it seems to be a broad generalization. Another useful device, but not suited to all situations, is the passive voice: instead of on dit que…, we can put: “it is said that…”