I personally think it'd be very hard for china to maintain oversea colonies, especially one in eastern South America, considering how much of their coast is dominated by Japan which looks like it's fought several wars with China already.
I propose china take a bit more India, that part of South America is given back to Poland, and give some other small bits of South America to others because someone ruling an entire continent this early that isn't Australia is weird. If you believed Eurasia was initially OP I really think you should nerf South America, especially considering that land is a lot more useful than Siberia's.