First of all, you need to be very clear on this: they do write things in English in China! If you are shock by this, you need to get over this very quickly. Secondly, if you are referring to papers written in another language other than English, then you need to be very clear that this is what you mean, rather than keep picking upon papers written in specific geography. The Japanese Journal of Physics, published in Japan, can be found in English and very much searchable in English as well!
Finally, learn about citation indexes! Papers that are written not in English will also leave a "trail" of citations, either papers it referred to, or papers referring to it! Even Google Scholar gives you not only the result of your search, but also the papers citing each of those results! It can't be any easier! Many of us old timers used to have to drag ourselves to the library and go through card catalogs and indexes to find the things we were search for. You have it at your fingertips.
Zz.