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 an extensive 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…”