Brit stuff
So just make them bolstered from the start and add the bolster costs to teching and reduce initial resources a bit. It’s really stupid ht the best infantry unit by far gets a slight nerf and all of a sudden everyone screams that it needs buffs like crazy. Bolster them from the start and be done with it, everyone bolsters within the first few minutes anyway.
As for the problems you brought up:
1) You buffed the Vickers and they still have the UC. People who still spam sections and then complain shouldn’t be heard. Again, don’t balance based on people crying over here, try the units out yourselves. Unless this comes just from your observations, in which case you’re right to bring it up.
2) Soviets also struggle against them but have the T70 to carry them. Perhaps you could make the M5 a stock unit?