I don't have Chinese in any of my pulldown menus or notifications. Google apps, safeynet, widevine 3, etc. all work out of the box, even on the Chinese rom. However, I did replace the launcher with Nova and disabled a bunch of Xiaomi apps with XiaomiADBFastbootTools.
Now, all that said, I haven't been able to get "Ok Google" to work for me. The assistant itself seems to work and I can prompt it with a key command, but it gives me a regional error if I try to have "Ok Google" always on. Maybe it works outside of China, but it seems to be a problem with rom itself.
I also have my international payment methods binded to it no problem (safety net works) but since I'm in China I can't really test it out anywhere. It works online, but I would want to see a physical NFC transaction go through before I declare it working.