Technically its 2 China's and tibet as the third China is being left AI'ed as being significantly stronger then the other two.
Tibet is China.
"With DW, land has become pretty useless, unless you have the magistrates to build a lot of stuff in it. Russia currently converts with more land than it can possibly develop in 400 years..."
I'm certain that this isn't as bad or as problematic as you think it is, 400 years is roughly 1600 magistrates, you can probably max out infra in 100 or so provinces, or more strategically manage 200 if you ignored the government buildings past the first 1 and maybe ignored trade buildings; as ming wit averaged 2.6 magistrates I could handle all the buildings thus far just fine, with 4.1 per year there wont be any issue at all.
Yes. Let's argue the mechanics of EU3 with von_Rundstedt...