Yeah, it looks like the Russian Revolution does need events to facilitate it. Although perhaps, if someone hit the Russians hard and often in the GC, maybe their humongous army wouldn't be humongous enough to quell the uprisings? You'd have to start that pretty early; I thought about it long and hard, but I'm pretty sure that even my large Scandinavian state-of-the-art army would be overran by the massive hordes the Russians can marshal. I bet they were pretty much just vicious peasants with pitch forks and torches, but they seem to have an endless supply.
ETA: It just occurred to me that in either of the games so far, I don't think there was a single Proletarian Dictatorship anywhere in the world in the early 1930s. How common are they in Vicky? (If I made a satellite out of Finland, they might turn into either that or a Fascist state pretty soon; I bought most of Finnish territory, and just about all of the farmer/laborer POPs outside my home region of Turku were either Communists or Fascists.)