Ballance of Germany is fully correct. And the other Countrys are done historically too with Manpower, Equipment etc.
The only thing is that the AI is not R & D the newest things which she is needing to equip her troops with or upgrading her Planes / Ships / Tanks etc. That you can only correct by Mods which get adjusted to the newest Game-Version atm. or playing Big Mods like the UMC-Mods. The Devs are working on it every Version but only a big refit / rework like they are doing now for the Airforce, Army and Economy etc. will get the farvored effect.
To come back to Question: Yes it is possible, the AI get the Chance about End 1942 / Beginning 1943 like historical. There the Soviet AI will get an Boost and the Axis have Problems to win then more Areas. That belongs to the historical things Stalin has done before: the great cleanup, get an threaty-contract with Germany etc. etc. etc. After Germany and the other Axis Staates raid the Sowjet Border and get so many Parts of Russia that the logistics break down and Stalin get his reserve as well as Production in Position then the Axis will making rollbacks.
And the other thing is that the Commonwealth and free World Troops open 2 more Fronts, which reduces your Troops and the other Troops on the Sowjet Border about 40 or 50 %. That´s the Trigger Time that the Allies and Cominterns will go back to Attacks and not only full Defense.
Good thats for the Game and how it works: The Problem there is, that the AI still have Problems with some Features there and so the Devs have decided to go make an big rework / refit etc. there in R & D (Army, Airforce, Doctrines, Economy etc.) and the Productions. How it will be looking we see after the Devs show us her Dev Dirays and new Vids.
But an Good example why the Allies and Cominterns needed so long to get an full functionaly War-Industry is that the economic Crisses and the Consequences from Stalin get solved first fully about 1941 / 1942.
I have seen a good Movie yesterday Evening, which get called AK-47 Kalasnikov or so. In that Movie you can see that the Sowjets have had a big Problem to get new Equipment for her Troops (like Planes, Tanks, Guns and most of all Rifles in all Terms). Not before 1943 they get new Equipment and a Production-Boost in Military Equipment. They had high flying Bombers which couldn´t shoot down and very good precission (yes Göring was not amuesd from that), some good medium Tanks as Prototypes and so on but 90 % of the Sowjet Troops were underpowerd (old Tanks, Guns, Rifles etc.) which had to be refited with more modern equipment.
Stalin had killed his good Personal or get them in the Goulags where they died, that´s the reason why the Sowjets fight so long with old Equipment. After you have seen that Movie on Amazon Prime and other Movies / Documentations we can talk again why the Sowjets needed so long to get the Offensive back.
Oh one more thing: If someone disagree there, have no clue about History and long Economy Effects. The second one we get again a feeling for about the World Corna Crisses.