There is absolutely no multiple currency conversion involved. If you have RMB then you can change it to whatever currency you want directly. I am from England and the rates are almost market rates, certainly much better than back in England.
I think you may have been confused by credit card payments in foreign currency because there I do believe it is converted to USD.
Hope that helps and please ignore our rather rude friend who thinks she knows everything and that everyone else should know what she knows.
It’s the internet and even pleasant people often become a**holes when they start interacting online.