It's no doubt Shanghai was full of spies and intrigue during 30's, but we all know how the situation in Asia developed towards 40's, so in that sense I doubt we will be seeing anything completely surprising in this show. Kuomintang (KMT) was ruling most of China (as much as anybody was ruling it during those times) until after WWII and their defeat by the communists (for whom Shangai was an important place), which explains why we are seeing lots of that tension in this show as well.

Still, I certainly don't know more of the Asian history than you do, but I'm not bothered by such things in this show as long as they make sense. Like those independence activists of this episode. People like that most assuredly existed back then and that's enough for me. Japan also had its own share of dissidents who were crushed towards the world war.