Do you remember when Wehrmacht meta was all about rushing flammen ht? It could come in 8 minutes and kill almost everything. I use it sometimes, with a pak or Puma protecting it. I suggest flame ht nerf, cost reduction to 90 muni and back to T2.
This caused the following:
Soviets usually have AT guns available within 30 seconds, not to mention their amazing mines.
In all seriousness I agree with everything, BUT, and there is a but. The problems you outline I wouldn't rank as simple balance issues, but rather results of some less then optimal design choices made in the game.
The problem with grens is because of infantry combat being too heavily focused on ranges instead of say cover.
Scoutcars are only effective with muni, well relic tries to avoid seeing 4-6 of them.
Pzgrens getting wiped, well we all get wiped. In my humble opinion I suggest this is a design choice to prevent infantry snowballing into the lategame. And give users ability to "come back" as Relic seem to be focused on.
FHT, see top and well there was a time when you as soviets got a quick Zis, and either killed the FHT or GG. That wasn't fun.
Agree with Ostwind, the unit is superfluous at best. But again more of a poor design choice in my mind. The Ostheer getting shipped with the OKWs AA halftrack would be a better choice for design.
Panther, yeah you said it. Call-in meta is garden.
105mm? Sure add some too it, maybe not CONSTANT barrage but yeah it isn't getting used enough. Altough I wonder if that is thanks to the unit being bad at what it is supposed to do, or if it just to easy to counter?
'105mm meet 203mm Precision striking B-4, his little brother the Precision striking ML-20, their cousins the IL-2 Bombstrike and Katyusha (also precision) as well as their foreign friends the Priest and USF artillery. Play nice now!'
TL

R I agree with the perceived symptoms but perhaps not with the cause and the fixes.