You're right : I do have devices on a xiaomi account configured with the China server. In fact, I initially had my yeelights and my aquara devices on the same account (configured with China server).
When I heard that yeelight could be remoted by google home if I switched on the Singapor server I decided to create a new account because I don't want to give up the use of my aquara devices (alarm, radio, temperature monitoring...). So I have now an account for my xiaomi aquara devices (mainland China) and a second account with my yeelights (that I want to remote with my google home even if I can't control them with my aquara gateway)
Is this possible ?