Hehe bottom line: if the US "stays home," Japan stretches from Japan to, oh, India or so, and the Soviet Union is the REST of the Eurasian continent.
Assuming, of course, that the Germans, fighting a one-front war and being area-bombed at night, don't hold out long enough to get their nukes built (an extra year or two, perhaps possible in the absence of daylight bombing and Normandy invasion).
In which case the Soviet Union is Eastern Russia, Japan still stretches to India, and Central Europe east of Germany to the Urals is a big radioactive parking lot.
So, let's just say the US had a "significant impact" on events during and after WW2 and leave it at that, eh?

Oh yeah, on the planes...
Re-do your count only don't count varients, and see how many "major, front-line" fighters are "missing" from the non-US planesets. With the exception of a few Russian planes, I don't see a lot of missing "major players" there other than bomber types. I'll bet they modeled the MAIN planes they had good data for, and are probably still looking for good data on the others, (anybody seen any reliable He-177 data lately?) And of course, the emphasis on the second half of the war is going to limit the number of non-US types to begin with, and make modeling the early planes from the other countries kind of a waste of resources...