Give the Pz4 an increase in penetration of 10/20 and it's in a great spot. I love to play with Pz4s and that's probably the only change it does need. To be more reliable against other medium tanks.
Reported bugs with the USF 81mm Mortar are currently being investigated and will be fixed as soon as possible.
So the reported bugs will be fixed asap, but the broken OP mortar with hyper accuracy and extremely fast shots will stay the same. USF counters everything with superb accuracy. Even squads in green cover get completely wrecked by it. prenerf ostheer mortar v 2.0 (perhaps even 3.0)
I do feel the OP's point, when you blobbed volks you could have squads x1 schrek, USF = squad x2 bazooka. With their latest buff they became really good for their cost.