I've loved this TL so far, but I find the premise of the Soviet War to be highly unlikely. Stalin was never a gambler and never started a war he wasn't sure he could win. I can see him bullying around the Baltics and Finland, but Poland had defeated the Soviet Union once before and their combined power with Germany, Hungary, Czechoslovakia, and Romania would be far too dangerous for Stalin to contemplate. Especially after seeing France's willingness to intervene in Germany and the disastrous consequences for the dictator there.
If you could replace Stalin with another Soviet leader, or place the blame on something like Poland intervening in Romania to prevent Soviet takeover and the situation spiraling out of control I could buy it.
Also I'm interested in how the war ended. How could they justify a negotiated peace after that many deaths? Also I don't think anyone else has noticed Leningrad is the Soviet capital. Was Moscow nuked? Were the Soviets about to finally break through Euro lines and the Europeans responded with a nuclear barrage? That could cause a negotiated peace. Especially if Stalin and Molotov died.