Good start, but Andrew Lloyd Webber did not write Les Misérables. The lyrics belong to Herbert Kretzmer! Good luck with the French

An interesting storyline, however you may wish to find a way to incorporate the French words with their translations (eg. in brackets directly after the french or by commenting on what the french meant in the next line). Although it is a creative idea, the french disrupts the reading process as the reader ends up having to scroll down to figure out just what is being said.
Another suggestion is to stick to the common French, such as "oui", "monsieur", "bonjour" etc. and the endearments that the French are so famous for "mon petit chou" (means my little cabbage and is apparently an endearment.).
Bearing in mind that speaking English in France at that period of time was a BIG no-no and that the British were often murdered so during that time period you'd find no-one speaking English... thus I would assume that even though you are typing in English, they are actually speaking French. Thus it wouldn't be necessary to type much too much in a language you're having to repeatedly translate.

Other than those few criticisms, it's a brilliant idea. Your characters seem to be developing a good structure to them and I can see no blatant spelling or grammar errors.
Best wishes to you and your story. :)
Will check in often to see how it progresses.
xxx