The first thing to note when you translate a prospectus from French to English is that it is bound to include boilerplate from United States law that has been translated into French. It's your job to translate it back into English correctly. For example:
la Règle S de la Loi de 1933
In English this is "Regulation S under the 1933 Act" but if you don't recognize this as a standard phrase in U.S. law, you could make quite a few mistakes:
You could mistranslate règle as "rule" when "regulation" is meant here.
You could mistranslate Règle S de la Loi as "Regulation S of the Act" when it is actually a regulation promulgated under (=pursuant to) the Act. Regulation S of the Act would imply that the Regulation is in the Act itself, when in fact, it is a separate regulation promulgated under the Act.
You could mistranslate la Loi de 1933 as "the Act of 1933" or "the Law of 1933" when the "1933 Act" is the common way of referring to the U.S. Securities Act of 1933 in English.
Reviewing the common terminology of U.S. securities law will keep you from mistranslating a blurb like this: une légende indiquant que les actions n'ont pas été enregistrées selon la Loi de 1933. This is a "legend indicating the shares have not been registered under the 1933 Act," but in a translation I reviewed recently the translator failed to recognize the word légende as "legend" and translated it as "a note to the effect that" the shares were not registered. These unregistered shares are in fact referred to in English as "legended shares," so "note" was a mistranslation here.
Sometimes a prospectus in French will use an English term that is not quite right. The one I reviewed recently referred to "non-delivery forwards" and it would be reasonable to assume that this is the right term in English, but in fact they're known as "non-deliverable forwards" in English.
A final point to watch out for is the English language's ability to stack nouns, which is impossible in French. Thus, the "NAV calculation date" in English is la date de la calculation de la valeur nette d'inventaire in French. When you are translating this phrase from French into English, it is easy to overlook the need to "stack nouns" in English. You might come up with "the date of calculation of the net asset value" (or even worse: "the date of calculation of the value of the net asset") when the right solution is "NAV calculation date."