The reason we don't see churchill's anymore is because of the pop cap nerf.
I played some Brits recently and was perplexed as to why the commander upgrade on their tanks, including the Comet, is still only a laughable "no-brainer" 25 munitions. Like come on - for better vision, on the move accuracy and extra vet xp..
I'd start there honestly. Then look at a minor relative armour nerf.
I think the commander upgrade give only a vision range buff and i'am not 100% sure but the xp gain was removed years ago and the accuracy buff is also so tiny that i makes no difference.