Imo medium tanks are starting to become "shock" units with high value when they first hit the field that is drops very fast. This are some suggestions in order to make this unit less of "shock" unit but add more value to them.
1) Delay the arrival of Cromwell, Ostheer PzIV, Sherman by adding 10-20 fuel to T3 and/or increasing research time.
Alternatively add a separate side tech.
Reasons:
The change will improve the timing to T-34/76 and reduce the shock value of these units. It will also increase the window of opportunity for light tanks opening the way for them to be toned down.
Issues with the lv weakness of Ostheer can be fixed by the reintroduction 221, redesigning of 222 a soft counter and lowering the power level of ostwind to 80-90 fuel while also increasing its AT capabilities.
2) Reduce the top speed of PzIV/Sherman by around 10%.
Reasons:
This is increase the mobility advance of Cromwell and T-34/76.
3)Lower the max range accuracy of TDs.
Reasons:
the probability of damaging mediums tanks from max range is simply too high
Sounds like it would kill off any medium tank usage beyond 1v1.