Churchill ain't broken. In 1v1 and 2v2 it's a risky investment at 19 popcap. It's less agile than a grandma with a broken hip. 1400 HP and "above average" armour of 240 pretty much make it a tanky tank that tanks, nothing else. You'll never see a decent player use Churchill on it's own. However, being effective in combined arms is not a proof of "broken". Broken units are those that can be spammed and close the game.
Its a prove that it shouldnt be blantly buffed, because all it can do make ppl switch from hammer meta to anvil one.
Right now its just not cost effective and comet is just a better option like always. This is pretty much the only two things keeping them at bay. They are not su76 or M20 bad, and they are not out of place like Pershing.
Imagine if Ost have had an stock chose between OKW P4 and standart P4 as an single unlock. Everyone would have gone for OKW P4, just because its a better overall option, but it doesnt mean that stock P4 is any bad of a unit.
Comet is good in any gamemode, not 1v1 and 2v2, its good everywhere. The only difference that in 3v3 and 4v4 you need to mass it a bit and the use it with somesort of an arty support and you can completly obliterate whole frontline.