Penal have been bandaided so many times that they simply do not have any design.
How is Penals' "design" being an alternative mainline infantry to supplement Cons any different? It's not like people don't go straight Fusies and No Volks like people go straight Penal builds. They also have two clear paths: either keep them vanilla AI or go PTRS route. There is also nothing stopping players from using them like P-Grens either and building several Conscripts/Engineers before building a Penal with similar timing to P Grens. Your concerns about the fact that they come in with Full AI power unlike Fusies doesn't have real balance concerns right now because 1) Penals are hardly being used right now so their early game AI power obviously isn't a balance issue right now 2) Nothing in the balance patch changes that right now aside from a slight T1 build time decrease
Just come to terms with the fact that the "design" of the Penal is basically a hybrid Fusie/PG that has it's own drawbacks different from them. IF they are used more it'll likely only be because their PTRS route is actually viable to use now and facilitates different strategies, which is a good thing. I'm open to nerfing them if the PTRS package is too potent (I'm leaning towards removing AT satchels or locking them to T4). But you really can't seriously argue that Soviets shouldn't have a stock infantry AT upgrade when every other faction has that option...
I mean I guess you could mold Penals into Fusies and have them start cheaper/weaker with a SVT upgrade package but I think that's a terrible way to go because it adds additional balancing problems and once again
Penals early game power isn't an issue