Lol. With Hong Kong being under British control until the 1990s, that means even Mao himself failed to get the achievement!
The system of who gets what in the peacedeal is weird at times I got nothing other times I got everything it depends on who controls the territory so make sure to do the puishback with your troops from your territory. Its really bullshit in my opinion it should be that the territory is awarded according to warscore.I'm still stuck trying to defeat Nationalist China. I can conquer Shanxi and Xibei San Ma before Japan invades, then I beat Japan alongside Nationalist China, but then my industry just cannot build an army fast enough to fight Nationalist China, Sinkiang, the Guangxi Clique and Yunnan simultaneously.
How have other people done it? Maybe it's easier now that Communist China gets infantry gear production bonuses (in the beta patch).