Kubel is not a hard counter... flanking is not a hard counter either...
Snipers, Indirect fire (like mortars, ZiS barrage), or smoke are the hard counters. Light vehicles for reasonable price (with teching) can function as a hard counter, especially if they deal proper damage like flamethrowers do.
OKW has NONE of these. Honestly if someone doesnt see the problem here, must be fully biased. USF had smoke nades, yet they received a T0 turbo-mortar WITH SMOKE, despite the fact it single-handedly made the PackHowi totally redundant. Not to mention they have doctrinal solutions like mortarHT and clowncars.
I won't disagree that the differences between EFA and WFA are obvious and problematic. USF mortar I still think is still a pretty 'wut' decision.
That said, the best thing OKW can do is really get a truck out and up ASAP for incendiary nades. Everything beforehand is stalling. And even then the incendiaries are to force one to pack up and move so you have more room to maneuver, not kill it outright.
Don't expect to hold territory as OKW like you would as OST. Cap what you can, slow down those maxims as best you can from taking territory. All you need is to get one Sturmpio in a good position to kill, if not steal, the Soviet advantage.
Soviet earlygame is a house of cards. They are rushing for their Quad or T70 just as much as you are for a Luchs. If the T70 or Quad comes out before you can get out a Luchs, skip it and go for a Puma to waste away their fuel usage.
Use the Puma to dive on maxims and drop smoke. (I recommend T2 truck first against Soviets. Soviets aren't static enough for early LieGs, even considering maxim spam.) But at the same time the indirect fire and barrage on some maps is all you can manage if resources are inaccessible.