Safari language problem

Safari 7 has been having an odd behavior on my Mac during the last few months. Note that I updated to OS X Mavericks a few months ago, using the Developer preview.

My main concern is that my menus are both in French and English. I want everything in French, but the top bar is in English (File/Edit/View/History/Bookmarks/Window/Help), and when I click on one of those, some options in the menus are in English, and some others are in French. It is very random. For example, the toolbar (under View), has 2 options : the first is in French, "Masquer la barre d'outils" (Hide toolbar), the other is in English (Customize toolbar...).

Safari is the only app on my Mac that is concerned. There seems to be nothing wrong with my Language preferences in the Mac's System Settings.

Now I do have a hypothesis, which could be completely wrong : I suspect the app Clean My Mac 2 to be the culprit. The app is known for sometimes deleting some files which are supposed to be useless to get some space back on the hard drive, particularly languages files.

Anyway, whether my hypothesis right or wrong is, I would love to be able to uninstall Safari before re-installing it, but I don't know if that is possible with Mavericks. As far as I know, Safari 7 itself can't be downloaded from apple.com, it kind of comes in a package with OS X, right? But I don't even want to think about installing OS X 10.9 all over again, just to get that thing right!

Any ideas?

By the way this is my first thread on Apple Support Communities, so hi, and thanks to anyone who reads this for all the solutions I've found on here over the years.