Brummbar leads to wipes if you don't retreat after the first shot, and it wipes out it's counter if left alone (ATG guns). With high armor and health you have to be pretty dumb to ever lose the thing while it bleeds you the whole game.
If your opponent has to get a tank destroyer just to scare it off, then you're down fuel/MP while he vomits on you. Even if you had 2 TD's, they won't gib it since it can survive 5 shots. In the hands of a good player you will never kill the thing. As far as fixing it? I'd at least sooner it take 6 AT shots but has lower armor or high armor and 4 AT shots. The high armor mixed with 5 shots is a bit too much imo. Guess its the issue of having Soviets share balance with USF/UKF.
On the churchill, idk what to tell you if you let that slow thing slunk over to your AT gun. If you get a snare off that thing moves 1 mile per hour. Maybe I'm just used to having my AT guns plink every other shot as USF. Does feel good reliably penning on OKW/Ostheer though.
Are you high bro. Every TD cost less than the Brum while also coming from a lower tech level.