USF Mortar Halftrack
For only 25 munitions you can saturate an entire area with white phosphorus which very quickly reduces all units in the cloud to an hp of 1 .
To make matter worse you can't just run out of the way as it for some ludicrous reason has a slowing effect. It's arguably even better than late game artillery as 2 or 3 m21's will waste the entire area and even a nearby medic bunker at a cost of 150 manpower and 60 munitions isn't enough.
USF M1 Pack Howitzer
This units accuracy is a major problem its just far too high it feels like everything fired is laser guided. 1 of these will easily do as much damage as 2 mortars at much longer ranges.
The white phosphorus is indeed very annoying to play against. Should probably just get a bigger munitions cost to be honest. The slow down effect wouldn't be that big of a deal if the ability was priced different.
Pak Howi accuracy is not the problem but AOE profile is. Right now it does both constant damage and wipes like crazy. So it's OP indeed. Keep accuracy high but give it less close and mid range AOE so it becomes less deadly while keeping the far AOE the same so it constantly does damage without wiping.