I disagree with your analysis–from what it sounds like, UK1 was played quite well. Ignoring Japan for a few rounds is not a problem. As far as I can tell, the main factors contributing to Allied loss were
—not contesting Africa (big one!)
—losing the British fleet (carelessness + your luck)
—Panicking on the USA west coast–your landing in Canada could have been handled easily
Sounds like there was solid Russian play all the way through, and mostly sound Allied play, but with the aforementioned oversights. If he had shut you out of Africa and not had to rebuild the USA fleet, I’ll bet Germany would have been about ready to collapse by the time Moscow fell. Generally the Allies can win if Berlin falls even a round or two after Moscow. I don’t think the idea of letting Japan go for a while and going full bore against Germany is wrong as a big picture approach, it just sounds like a couple of the details were botched.