At this time,overall, there is no weak rear armour for heavies. Mostly it is harder to pen rear heavies armour than it would be.
It is especially true for super heavy.
For exemple just consider any gun would have the same chance to pen side or rear tiger armour than it would have to pen frontally a PZ IV H. Here PIV H is considered at bk as 80 mm frontal qrmor even really it is false. PIV / tiger comparaison is almost true with US 76 mm vs 80 mm, with an advantage for tiger rear armour. It become a joke with the same gun attempting a rear shot vs an elefant.
Point asking compensation for heavies is mostly a benefice for axis side.
My comment is just technical, I have no balance consideration here. BK TT have many flaws, mains are there is no real rules and no harmonisation. Shortly bk TT tend to simply follow/ have no standard.