The feeling I've gotten is that there are internal communities in China, Russia and possibly Japan. Then there is the rest that clumps together in English. I'd love to get some confirmation of this though, as it is just my hunch.
When you think about it, there is almost a unidirectional knowledge transfer: plenty of Chinese people will study and work abroad and then go back to China. By comparison, how many people do you know of who do the reverse - in terms of ratios, how do these numbers compare? Open source code and academic research is all out there in English for people to read and absorb, but China also has the scale and funding to then internally propel these ideas and then publish in Chinese (if at all).
Though it sounds like there is some degree of open source and that Github is mostly the defacto in China too.
It's not just some degree, afaik Chinese companies have been really embracing open source [0]. Some argue this is the result of the Chinese cultural perspective that ideas are not owned by anyone, which open-source perfectly aligns with. [1]
[0] https://www.linuxfoundation.org/blog/2016/02/tencent-and-why...
[1] https://www.forbes.com/sites/forbestechcouncil/2018/10/25/th...
But it's haphazard. Most universities are incapable or unwilling of even running an email service and all emails go through QQ. That's not 'QQ for Domains' but just personal QQ numbers.