I do not like AT HEAT shell because they are actually very good AI also. I would rather turn them into a passive ability that either increases the penetration values of the guns by around 10% or adding 25% deflection damage. But I have not got to that commander yet.
Might be a way to go, but passive buffs are not great design since they require no input. Switchable rounds like the Jackson ones could be useful instead, but this would just again copy mechanics from other factions when there is no need to do so.
The current shells are fine in my opinion (I don't own the commander, so I can just talk from the receiving end), I just think they should not go on a JT.
Could you explain how they are too good vs infantry? Do you mean because of the 30% damage boost on e.g. the P4? That should actually be fixable by target table or a modifier on the AoE damages (0,77 will return the damage value back to 1).
Overall players buy them for the AT damage though, so it is a rather small issue imo. Especially since OKW has no dedicated late game AI tank.