Here’s a potential hosting option with their Singapore (SIN-01) location that seems to be reliable. I don’t know what the min specs are for the build server.
https://www.leaseweb.com/cloud/public/virtual-server/configure/29393
AWS also has a Singapore option now too and that may be what you want to use / maybe the Defold foundation can set up a build server there / pay for it so that Defold is more accessible to people in Asia.
There are entire GitHub mirrors being hosted in Asia. As in they either proxy or scrape everything and rehost. There is a security liability in using them but they do exist I remember seeing them before. https://hub.fastgit.org/ seems to be one but I don’t know if you should use it, you could ask general coders in China what they may recommend.