Hello Mathieu!
Sorry about your hundreds of non-modular files. :( Hopefully, we can help a bit. :)
curl.js has a utility for loading non-modular scripts. It is the curl/loader/legacy module. It works great. However, if you're new to modules, then you might need some advice to set it up for hundreds of files!
You say you need to load these modules sync, but I doubt that's strictly necessary. I'll bet you could find a way to configure curl.js to load the scripts in the right order. Of course, this job would be much easier if you could concatenate the hundreds of files into a smaller number of files. Do you think that's possible?
If you are planning to migrate your code base to modules, then curl/loader/legacy might be a good way to start. If you are not planning to move to modules, I suggest you look at LABjs.
If you think that you want to move your codebase to modules (even if it's very slowly), then let us know. :)
-- John
P.S. your English is fine!