I'd not say penals are overperforming. They are stronger than most mainlines, yes, but they cost 300MP, so they should be stronger. Also, PTRS gives them some power vs vehicles, but only vs LVs. They are bretty bad vs mediums and heavies.
Penals are not mainline inf. Also no infantry deals easly against mediums nor heavies, i mean, if penals could, they would be OPAF. I dont understand why you bring that up.
Plus, when they get PTRS they drop significantly at AI. AT satchel is hard to use vs carefully playing opponent. If u take T1, you need to fast rush to T3 to get some reliable AT, or backtech to T2 if your resourse control is not enough, or else you wouldn't be able to counter tanks well.
Thats something useful, in order to scale up into midgame, AT is neccesary. Also you have gathered many penals squad by the time 2-3 of them have PTRS, so their AI hasn't decreased that much, even nothing at all.
I'd say penals are not overperforming, but overused. That's mostly because using cons is much more difficult. I thought about making penals something like osttruppen, it may make soviet infantry play more variative.
If OKM obers could be trained at T0 after 1 SWS is called in, it would be the same thing as penas right now. Expensive but effective.
Man, they only cost 300, its only 20 more that USF riflemen and penals do wreak havok. Its a little overperform IMO.