For Korea, I would advise to just stay away from anything from Gojong/Myeongseong/Daewongun period, too much of a political material there. We might see an uproar on a national scale of Firaxis picks anyone from that period in Korean history.
For China, Dowager Cixi covers the period of Chinese history that has always been a big deal and even more so as China returns to its previous position as a global superpower. Much of the focus in China today is on reversing the humiliation it once faced in the 19th Century and returning to its formal glory. Although not always a positive icon, she is far more iconic for Wu Zetian regardless, for some as a symbol the Chinese imperial family standing its ground rooted in tradition, for some as a symbol of inability to modernize as much as Japan, etc. The Chinese resistance to Western colonialism itself tells a thousand tales, in which Dowager Cixi can embody as some Dark Age bonus. On the other hand, Wu Zetian just happened to be someone extremely competent, period.
I never said that Qin Shi Huang and Mao Zedong are "awful" picks, but if they're really looking for underdogs (as they did for Japan and France at least) they should do more research. China happens to be a country of exceptionally memorable leaders across history spanning five millennia.
The Taiping Rebellion was rejected by the West by theological disapproval but who knows, the real reason might have been again colonialism. Nevertheless, their ambitious project of creating a Heaven on Earth was what influenced a future generation of Chinese Communists who became influential enough to be a major player in the Cold War. On Gender Equality the Taiping had some radical views there too.