Look, I get that I'm bad at the game and I'll never get good, but are you sure the KV-2 is balanced and has a clearly defined role?
Id say it has. It great heavy tank that turns infantry to mush and makes any medium scale tank regret coming in front of it. It has infantry fighting boost and can become effectively mobile ml 20 with the ability to stay in place to increase range and reload.
So it can be breakthrough tank or defensive powerhouse, depending what units you surround it with. Only real limitations come when vs other heavy tanks, but its not as big issue when you build army to help against that.