In context of general Penal performance.
The Soviet tech order makes T1/Penal and Conscript/T2 builds virtually exclusive at least until after the beginning of the mid game. Back teching T2 before the first tank is only done when you're already knees deep into trouble. So until that point, Penals need to fill a lot of holes or at least make up for them because the current AT options of Soviets are not viable until the SU85. Soviet T1 builds in the current version are quite tricky to play, and as you say they usually need support by commander units. Two mainline infantry units in the same faction are not bad design by default, but I think Vipper is right that at least the current implementation of those two has just been causing issues for the last years.
I believe the problem stems from mid game lack of scaling.
You just can not have mainline inf that is reliable and relevant across whole game without weapon upgrade.
We've strolled this road for years with conscripts, now we're going for a 2nd lap with penals and their mid and late game viability.
Lack of upgrade to keep infantry scaling through early mid game and extreme over reliance on T-70 to jump back into the game once everyone else starts rolling out infantry weapon upgrades is a direct reason why T1 feels bad on the long run as even if SU-76 might be a good option right now, as long as there is no infantry scaling to fend of the pressure, it will always be T-70 and in turn, T1 lack of AT reliability and AI scaling.
I am quite interested what the current changes will bring. Maybe those slight buffs to AT Penals and the SU76 are enough to bridge the gap for T1 builds, maybe they are not... But in the end I the weird spot of Penals/T1 in general still remains unsolved.
I honestly do feel like it'll take a while longer, but a solution akin to mobilise reserves will be employed for them. PTRS buff does a lot to their AT part, but -2 reinforce cost and vet swap isn't going to cut it at all in AI department, they will keep on bleeding to vehicles and not doing enough to infantry due to abundance of cover cutting their DPS drastically.