The current Soviet commanders render the tank buildings almost worthless due to the fast rise of CP's mid-match. By the time you would build the tank building (either/or) to produce mediocre units (such as the T-70 and SU-76), you most likely already have the CP's to call-in tanks such as T-34/85's, KV-8's, IS-2's, and so on for other commanders with tank call-ins. It is worth noting that these call-ins have no production time, allowing for, especially in the case of t-34/85's, a good grouping upon recruitment. As a result, teching up as the Soviets is generally an inferior strategic option for Soviet commanders. These doctrines allow for victory in multiplayer, but leaves the majority of non-doctrinal Soviet troops, especially tanks, invalid and inferior choices overall.
While I won't disagree that CP gain is still too fast and that waiting for call-ins is still a somewhat dominant strat, saying that you have CPs by the time you build T3/T4 is just hyperbole. No matter the match you are likely to get 2 vehicles minimum out of them before you hit the CPs where you can call in.
I propose that the tank tech costs for Soviet tanks be reduced. 120 fuel is an extremely prohibitive cost, especially given how mediocre the units in the buildings actually are. For example, it is cheaper to build a StuG III in terms of fuel than it is to build an SU-76, given the cost of tech buildings.
Wehr tech cost to T3 + Stug:
200/45+200/55+80/10+160/25+230/80 = 870/215 (You probably want to add in 120/15 for T2 in almost all cases, but lets pretend you're just rushing StuG)
Soviet tech cost to T4 + SU-76
160/40 (or 200/50) + 240/120+240/70 = 640/230
EDIT: Fixing my super math.
TL;DR Restructure Soviet vehicle tiers from light to heavy tanks, including the T34/85’s and the IS-2, so that players aren’t forced to choose between doctrinal units and two worthless buildings. Arguably the best unit currently from either building is the katyusha, and that’s just odd.
While it would certainly solve issues with non-tank call-in commander viability, the balance issue problems are just too massive for this to ever happen short of a complete redesign of all units mentioned and soviet commander ability selection.