This all seems to assume that the western Allies leave Russia to it’s fate. But assuming they control the seas the Allies can send troops to wherever the CPs are attacking.
Russian forces concentrated early in Belarus can crush any invading army and then reinforce the survivors more easily than the CPs can send fresh invaders. If Russia is in trouble the UK can send forces up through the Caucasus or by sea via Karelia.
The plan is based on the program of Crush Russia then switch forces west, but if the Allies are awake the CPs simply don’t have time to do this before American troops reinforce France/Italy.
I still feel the best rework of this game is the CPs given set victory targets at the end of specific turns; essentially they must “beat the clock” before victory becomes impossible.