Nice idea, we just don't have that kind of technology yet .Joking aside that is really a nice idea would just remove the heavy engine one, which for a heavy tank migth as well be dead for the speed it moves, and also use the same formula for the t34 itself, say if it rams and still mantains above 75% hp the t34 gets only a stun while a low health one just gets killed for the rodina.
Aye, I was trying to think of an alternative for HED but I really wanted each tier to have something. Although HED wouldn't be awful at 25% since it would effectively be tossing a tank at an already "dead" tank to ensure no RNG shenanigans (I had a JT escape with a sliver of health because of bounces even after being rammed and maybe I'm salty)
The ability should work simply without any conditions. Either the ability works, or throw it away. There is no need to invent complications where they are unnecessary.
Working dynamically is still working. It would ensure risk and reliability instead of simply RNG and/ frustration due to unpredictable or underwhelming (over overwhelming for that matter) results. It's effectily a compromise between the way it was and the way it is now allowing it to be used to good effect at the right time without outright invalidating anything too slow to get out of dodge