First thing I'll mention, if you click
HERE you'll see that the site is encouraging foreign language games this Spring. I'm not sure at this point if anyone will be writing any, so if you wrote something decent in French you might be able to single handedly rescue this sad dud of a jam.
Unless of course you meant it not as an issue of language, but rather were implying the French are just bad writers in general. In which case, well alrighty then, I certainly would not want to be the one to contradict your lived experience.
Otherwise, what Wizzy said, get a decent amount of writing done first, and then make a thread on the Writing Workshop asking for help. If the story is set to Sneak Peek in Storygame Properties, all you have to do is provide the URL and anyone can read over it without you needing to publish it first. (Or co authoring is a possibility that would let them edit directly, but only do that with someone you trust.)
And also, yes, reading some of the more popular games to get an idea of reader expectations is a good idea. CYS is all community driven and readers here tends to have higher quality standards than most other writing sites you might be used to. It's a really good sign that you're thinking ahead to the need for a proofreader actually.