I just simulated on my Pc and I would say that there are 2 possible options to your problem.
1- It is possible that your windows for x reason have changed the default language. Under Win10 I added Italian and put it in default language, so everything launches and starts in Italian after rebooting, for the SW side you can check or check use english it won't be useful because I didn't tell SW to install the Italian pack, Basically, if he can't find a language other than English, he stays in English. if I had installed the Italian pack my SW would be in Italian. Which leads us to the 2nd point that we have to control right away.
2- Instead of running a repair (which is only used if SW doesn't start or doesn't start properly), you have to run a modifier and in the SW options check that the French is checked. (see photo)
I hope to have helped you solve or eliminate a hypothesis.