I imagine they are managable in 1v1s, but in team games it can be incredibly hard to deal with Churchill/TD combo because the Churchills just won't die and even deal out good damage of their own while TDs in the second line can freely engage all Axis armor at max range. Not saying they are OP, but they do seem to have very good synergy with the Allied TD meta and I can imagine people struggling to deal with them. Especially since most AT (Pak40, Panzershrecks) seem to do nothing frontally and rakettens are just laughably killed by a Churchill casually driving up to them and throwing the grenade.
Sorry but I cant imagine an scenario where churchills dominate in team games, specially when there is twice the axis stuff. I play mostly 1v1, but I play team games sometimes. If you are engaging a churchill with anti tank guns and you dont have a squad with panzerfaust nearby, you are doing something wrong. Churchill in my opinion is probably one of the most balanced heavy tanks in the game.
Aside from being a necro response, if you have the proper tools then yes they're more or less manageable. The problem is that these "tools" are the StuG and the JP4, which both boast RoF to deal with the large HP pool. If you get these tools they have limited use against tanks only and no turret, as opposed to what the churchill offers in AI/AT and very decent armor and large HP. I wouldn't call it the most OP unit in the game, but these kinds of units can really snowball if you get caught offguard since there are so few real counters.
I didnt revive the thread, look up. If you are only considering JP4 and StuG in the formula to deal with the churchills, you should reconsider the way you are analyzing the threat. Mines and panzerfaust are the real dangerous thing for the churchill, specially how slow they are.