Use the AP then. Sherman AP shell has better AoE profile than the cromwell.
You don't understand, Sherman HE shell is a poor's man shield. I personally don't think it is that better than the P4, in some specific circumstances probably but anytime a P4 is nearby and you don't have an Atgun close-by then the P4 is better because even if it deals a little less AI damage its a threat to anything with the same type of shell and superior survivability.
So at the end, every time the P4 is fielded the P4 is better.
Look at the top players, what do they spam every time they play Ostheer once they reach T3, the P4 and then call-in a Tiger. What are they doing when they play USF, 2xSherman76 with maybe 1 M4A3 and then Jackson.
Statistically, on paper, the sherman is great vs infantry but its an overkill to mask the reality that the tank deal poorly in any other aspect of the game and at the stage it hit the field what you need is something consistent on which you can pivot your infantry, not an overkill AI tank that translate terribly into the late game because of its inexistant survivability vs late game units unlike the P4 that will continue to pose a threat to the Jackson, Firefly or Su-85.