That sounds like your initial scrape was incorrectly done, probably the language settings on the scraper were wrong.
So you're basically replacing the local (English) data with the current scraper settings, which are presumably French from what you describe (and as you want them).
The data is not in the folder unless you've exported your database as individual files, which will write
NFO (wiki) files beside each media item. The information is in the Kodi database, which is either SQLite (by default, stored locally as part of the install in the
userdata (wiki) folder) or
MySQL (wiki) (if it's been set-up to be hosted externally for sharing between installations).
If your database is in English and you want it in French, you may be best to dump it and start again with a fresh scrape using the scraper set up how you want it (to scrape French language).