First about howitzers:
- Ost has 2 (Edit: sorry there are 3) out of 22 commanders with 100% destruction plus 1 with a decent chance
- OKW has 4 out of 9 commanders with 100% destruction
- Soviet has 2 out of 22 commanders with 100% destruction
- UKF has 1 out of 9 commanders with 100% destruction
- USF has 1 out of 9 commanders with 100% destruction plus 1 with a decent chance
So Ost is just about average here, only faction which stands out is OKW. So there is no reason for me to rework only Ostheer at this point.
I think you got the numbers wrong.
OH:
Railway artillery: 2 (first shot guaranteed 100% accuracy)
Fragmentation bomb: 3 with say like 15/20% chance to destroy it, most of the time it's decrewed with like 10/20% HP left
Soviet:
PTAB: not reliable at all. Too much scatter. But sometimes (5-10%) it destroys it or damages the weapon to 0% HP but crew is still alive.
UKF:
Precision Barrage: 1
Concentrated Fire operation: 1
Air supremacy: 1
Concentrarion barrage: unreliable but will get it decrewed and highly damaged (similar to OH fragmentation)
Then there's plenty of other abilities which will get the weapon decrewed but not destroyed.
And as Vipper mention, there's also some units which can call offmap but those can have a harder time reaching objective.