Not talking about team-games, exclusively 1on1.
I agree that there are issues, but I will adress these as good as I can with my knowledge, since some of the issues you describe aren't really the problem.
1. Riflemen and RE outclass Volksgrenadiere and Sturmpioniere early on. Even with the best micro Volkgrenadiere have no chance against Riflemen no matter what range. There is no AI option early game for OKW. No sniper, MG, Mortar etc to counter. This allows USF to control the map early since in order to beat one of their squads you need two Volksgrenadier squads.
Early map control and flexibility are USF's strengths. Later on, Volks will outclass them with vet. The key is to get there. Also on long range Volks
do win against Rifles very reliably. This is rather a map pool issue. The more cluttered the map, the more you need to be mindful and careful when facing Rifles.
2. Sturmpioniere can´t reliably 1on1 Riflemen unless you ambush them.
They aren't meant to. Sturms are the key to face aggressive USF in cluttered maps, so I will agree that you need to ambush them. This works great when you manage to do it, but again. Sturms outclass any other engi squad and unlike any other engi unit, can even take on Rifles underthe right circumstances. Their price and upkeep reflects this imo.
2. Kübelwagen die super fast against USF more so than any other faciton. Now maybe it is just me but RE do so much damage to Kübelwagen. If you shoot at a RE squad with Kübelwagen you can maybe kill 1 or at best 2 models before being almost completly destroyed.
I don't believe this. REs are good at long range, but their overall dps is miniscule, so unless there is cover or any other deviation from a "standard 1v1" situation, Kubel should win this reliably.
3. Luchs and Stuart hit the field at roughly the same time. Luchs is the only chance you have to effectively kill USF infantry but is countered by the much stronger Stuart. If you go for Puma you can counter Stuart but have nothing AI while Riflemen eat your Puma with their bazookas and Riflemen rifle grenades.
This is a valid point imo. This wouldn't be much of a deal, if Raketens weren't so fucking unreliable.
But the problem isn't Luchs vs. Stuart timing, since Luchs is that much better at anti inf. It's probably worth mentioning here, that Riflemen AT nades are very good at keeping Luchs away, whereas Volks faust are kinda short ranged and can't achieve the same effect on the Stuart.
4. Riflemen can lay mines. That means that it is super easy for USF to mine the map since they have multiple Riflemen squads at the same time while OKW can only mine with Sturmpioniere which also need to repair tanks and help your infanty fight.
Riflemen mines are doctrinal, so that puts it into other territory in terms of balance discussion and I wouldn't quite call it an issue in the general balance matchup. I will agree that Sturm are indeed working overtime right now, because Raketens are unreliable, Volks have no more Schrecks and repair now comes after a little side tech, so Sturms must repair in the meanwhile, but you might need them elsewhere.
5. OKW MG is a horrible piece of trash that needs to be buffed. It is amazing how bad it is when trying to control USF infantry. USF MG is again much better.
OKW's MG34 used to be doctrinal and I still don't see them as essential OKW unit portfolio. It's good that OKW has got
asuppression platform, but I like the fact that it's not as good at what it does, since OKW isn't built around having it. Same goes for the USF mortar, which I will adress below.
6. That USF mortar. Enough said.
As with the MG34 for OKW, USF was not supposed to have a mortar. They still got one, after the community tested and agreed to have a light mortar, that was supposed to be a mobile, light damage mortar, that's main purpose was to provide smoke. However, after the testing lelic decided to implement this broken mortar, which will be hopefully changed to be what the community agreed to.
Whenver I play OKW vs USF I feel like my opponent has a super easy time to fight me while I have to come up with lots of tactics to even stay in the game and get a single medium-tank out. It feels totally unbalanced. And the worst is: Often times you can just tell that the USF player has no skill at all and beats you just because his god damn riflemen and Stuart are way better than their equivalent.
Overall, I would count most issues you listed as invalid, except for the mortar that you mentioned rightfully and Stuart dominance. The Stuart will hopefully be kept more in check when Raketens will be more reliable
eventually and in the same way
hopefully the USF mortar will be changed in the right way. Keep in mind that my comments are based on my own limited experience and I don't claim to have figured it all out, but after seeing numerous top level players face each other, the key issues with OKW vs. USF seem to be the risky T3-rush tech vs. underwhelming heavy-T1, the overpowered USF mortar and most importantly Raketen unreliability.