While I am happy about the Far East being treated more significantly than four unfriendly civs wasting space, my concern is that it might be very hard to code dynamic aspects of the Far East.
In "vanilla" RFC, AIs can only occasionally occupy other civs' lands. For example, when it's not used by a human player, Rome often doesn't conquer any Greek or Carthagian city, while it starts with extremely strong military. Similarly, I don't think it's easy to code so that the Qing defeats Ming. It will be even tougher if we treat Qing as "the Juchen people," since the Juchens should be around at the start (1450) as a rather weak civ and somehow become stronger than all the others in China. Furthermore, it's also very hard to move all the vassals of Ming to Qing.
Also, to be historically accurate it's not Ieyasu (Tokugawa) who united Japan first and invaded China + Korea. Hideyoshi did those, and Tokugawa later betrayed and defeated Hideyoshi's son. But, it would be presumably difficult to code (civil war -> unification -> international war -> civil war -> unification) if we are to represent civil wars in Japan. Furthermore, because the AI is so bad at naval invasions, Japan probably won't invade China or Korea effetively, while
the history of Ming states that Ming and its vassal (i.e., Korea) had no chance of winning the war but the death of Hideyoshi ended it.
Other than that, the Far East is problematic in tech. To be historically accurate, China should start with Printing Press and Gunpowder. This means that they can very quickly go for Rifling. However, to be historically accurate, the Chinese did not discover such technology. They must somehow become weaker in relation to other civs. In Japan, too, Tokugawa refused to trade with most foreign coutries with very few exceptional countries which did not try to spread Christianity in Japan (e.g., Dutch and Portugueses), and severely slowed down technological advancement. It is also hard to code if one cares about historical accuracy, since both Hideyoshi and Ieyasu were very willing to trade with most European civs before they united Japan (then, after the unification, they started to hate Chiristians whom they saw too fanatic).
Maybe we need to decide how much accuracy we need.