Oh geez, just give it up already!
You want the fantasy of being able to call in one of the fanciful units? (and it is a fantasy). You will have to deal with the fact that Allied counters will have to also become commonplace.
What I am saying is if the Axis get the fancy kit the wehraboos want to fap over, and if that fancy kit actually works in the game as it did in the designers mind rather than on the battlefield, then the Allies will have to get a counter.
Your choice... do you want it to be an equally fanciful working allied heavy tank design or 4-5x the mediums. or do you want to have a 10% die roll at the start of an engagement to even see if you get to call in a heavy at all?
This has to be bait at this point, but I'll bite
Its a basic rule for COH at this point: If a few (20+) were made, and it saw atleast some major combat in WW2. It can be in COH.
This is why the Sturmtiger is in. Its why the Flame Hezter was in, its why the Pershing was in, its why the Comet was in, and its why the Black Prince should NOT be in
And as for the battlefield operational problems, literally every faction had horrendous tank problems. A good chunk of T34 and Shermans were lemons on the field. Tigers were stupidly over designed for no good reason (I.E adding 50+ moving parts to save 10 pounds on a 50 ton Tank). Churchills intentionally had limits put on their engines so it couldn't go faster than running infantry. WW2 was literally the first major conflict that used Tanks from start to finish. Ofcourse everyone would be experimenting and failing at tank design. it was a new concept.