Getting back to the topic of mechanics, I think the politics side of Europe 1940 is pretty broken.
The USSR remains fairly weak (relative to the Germans) until they’re at war, but basically the Germans have full control over when that war starts. To the point, the USSR cannot benefit from any of their N.O.'s unless they are at war… so even if they’re given the full 3 rounds to build up, those are done under the circumstance where they’re the weakest.
Germany doesn’t need 3 turns to mop up France, Yugoslavia, and Greece, so the extra money/units they produce over that time is just gratuitous, relative to what they actually require in order to pound the USSR into dust. The fact that there’s a German N.O. for not being at war with the USSR just adds more fuel to the fire.
Another mechanical complaint I have is around scrambling. From a balance perspective, it seems like something where the rich get richer and the poor get poorer; from an actual procedural/gameplay perspective, it also slows down the flow of the game. Everything has to grind to a halt so that the players can decide whether or not to scramble, and how much. I think as a general observation, Axis&Allies needs less of these sort of mechanics; the game greatly benefits when automation can speed up the rate of play, and this kind of thing has the opposite effect.
Like sure, you can put in orders ahead of time, like “only scramble X if Y” but the game doesn’t need that level of fiddly-ness.