It's Ostheer that's underperforming in every stage of the game.
Fragile infantry (Grens) that can't compete with BARS and Brens.
Lackluster "elite" infantry (PGs) that can't compete with Bars and Brens.
Inferior midgame (T70, Stuart, AEC leave you on the back foot).
And a lategame that is mediocre at best and absolutely inferior to Brits (Tiger, Ostwind < Churchill, Centaur). Aka no reward for holding out that long. It's characteristic, that Brummbär, Elefant got significant nerfs while multiple Allied lategame units got buffs/ stayed the same. Ost lategame was neutered for no compensation.
And before I hear the "l2p" posts, I'm playing this game and it's predecessor for more than a decade now. I know what I'm doing.
I will say that you're cherry picking. Only mentioning ostwind-centaur when the p4 is clearly superior to the Cromwell for pittance in fuel.
Comet being utterly trash with non existent vet compared to panther. The existence of the pwerfer to wipe support weapon walls when UKF have no non doc indirect fire.
Then there's non doc answers to everything early game, sniper/mortar/smoke/flamer pios/elite inf. Basic tools that factions like Brits and USF lack.
I don't doubt double bar rifles destroy grens lategame, but ostheer are hardly this little puppy you are making them out to be. Maybe some people need reminding okw had a 80% 1vs1 win ratio vs Brits before they got snares, Ost numbers were somewhere around the 68 mark. (Even Hans abandoned Brits)
So I don't see how this one change and some doctrinal tweaks have suddenly made axis useless.
The game just needs small adjustments at this point, it's in a much better place balance wise.