Those are countered just fine by both Panthers. In fact, I don't think it is a good idea to build stugs to counter those units if they come in number, Jpz4 is probably better in that way but that's an other topic.
Agree with you to a certain point but Lvs or not Ostheer and OKW always have access to pak/raketen to support their Pz4s so I find it questionable that Pz4s became better AT than the sherman over the time when they have all support access from previous tier + the possibility to build a dedicated medium counter.
As for buffing the Ostwind, I'm not against but who would build a Ostwind over a Pz4 if not by itself OP in a sens that the Pz4 is already strong vs infantry and strong vs Armor. Say you put the ostwind to Sherman HE level, people will still prefer the Pz4 for its AT capability and still good AI capability.
First of all, i dont agree at all the way you mix arguments with excuses, since you do not only not care about how the other faction manages to react to any USF offensive but you deny the fact that such play done properly should be ablo to stop you from gettinv your objectives. Its a double fallacy. Its like sayin "if you raketencheese with 4 or more you instakill a sherman, and still i dont understand why raketen can cloak and kill tanks" this kind of sentences are in the far espectrum or logic arguments agreeable to others PoV.
Lago laid out the situation in a neutral PoV, and he tried to explain why pz4 have an edge in AT, sooner or later OST vs USF needs it to keep balance. As for oswind to be a inf counter it would be very healthy for the sake of the game variety, but thats offtopic.
Again shermans afe not meant to be superior since USF have either better options in the same time mark or for lategame, they still set the pace of the matchup, since riflemen can put so much pressure and a stuarts just boosts that power. Shermans are more like a reactive play and a neutral one rather than being still aggressive.
If shermans were to be ablo to keep that USF pressure power they must be HP nerfed, acc nerfed and become a risky choice rather than a safe one as it is right now