I know Chinese government doesn't really like google as i have had issues with implementing code for Chinese clients, at least some google APIs do not work there.
Does the libphonenumber library and/or it's lightweight version libphonenumber-js work from within China? The question is not about them being able to parse/format Chinese numbers, but if they have their full functionality from a Chinese IP.
libphonenumber is just JavaScript code; it does not use network or HTTP.
It can run from anywhere.