Add-ons • Re: Translating French web pages back to English

What you want, instead, is a translator extension ... Otherwise using Google Translate or similar web-based translation services and feeding them the French page URLs might be a solution.

Despite I do not like the G***** things, Google Translate does a fair job translating an entire page (giving the URL) preserving the visual appearance, at least between the main languages. I once used it to translate back from Russian to English a short 1975 SF story by Harry Harrison (Гарри Гаррисон ) of which the orignal text is not available.