The best solution I can think of is to buff the USSR while nerfing the USA. This is a very delicate balancing act though, as too much will make it extremely difficult for the axis to conquer the USSR
Prove that change is necessary in the first place. The results suggest that's not the case.
You can't build entrenchment in marshes,
You can, and should. Further more, to compensate for the malus against air attacks, you can and should also upgrade the fortification with AA.
Even after my game against KZ in WiE, after the whole community agreed the balancing to be nearly perfect, there still were demands for changes, and no Axis player stepped in. I didn't take that seriously and ignored it, but those demands were granted, and for the worse of the game imho.
The changes in the latest updates seriously complicated the handling of supply. While this has been an issue for a long time already, it`s gotten far worse. From my perception 90% of the players have no clue how to handle supply, one of the most important features of this series. And it's affecting one side far more than the other.
I am probably the most experienced player of the entire series, and I can comprehend completely players want to play at first before studying the rules; but even if I`m losing against more skilled opponents, I wouldn't blame the game for my deficits. At least I know them very well, and if any opponent takes advantage of them, they deserve to win, that's what strategy games are about.
My suggestion: learn the supply rules at first. This will give you in many cases a serious advantage above most opponents; and if that's not already enough, there are many more things to learn. This game is very accessable, but far deeper than you think.
I'll try to make a rookie tutorial regarding supply.