1.its ahistorical America couldn't have a civil war in 1937
Yeah, kinda like Germany and Austria still having their Kaiser and dominating Europe, having a Russia republic that can very easily return power to the Tsar, having the Ottomans still going strong, leftist states in France and Britain, half of Africa under "direct control" of Germany through good'ol Goering etc. I can easily see where you're going here.
- People are saying America is "overpowered"
America *is* overpowered, there's no arguing here. Both in the base game and in Kaiserreich the devs took steps to avoid them coming knocking on the doors of the world by the end of 1936, in the first case by having them go through a painful process to exit the Great Depression, in the second by having them thrown into a civil war which is supposed to be "the great war America gets involved in", just like all the Italian states are not really supposed to take part in the 2nd Weltkrieg but rather fight for their re-unification.
I don't even know what this is supposed to mean, let alone figure an appropriate response.