How does Stripe deal with the currency conversion? Is this tracked by Alipay on an individual level (i.e. so consumers can't spend more then the legal conversion amount of 50k USD)?
I think you may ask for a higher limit but usually you just use family accounts.
Paying with a multi-currency credit card has nothing to do with this limit.
In your example, if you have RMB in your China bank account and withdraw RMB overseas, these are no currency exchanges at all. It's not relevant to the $50k exchange cap.