That is simply inaccurate the comparison was about abilities and not the units
But there is little reason not to compare the units to begin with:
Stug/SU-76 and JP are unit in the same category. Actually SU-76 and JP have same range and similar penetration/ROF while Stug has 10 less range.
Su-76 has utility, mobility and price on its side while JP has Armor/HP/target size/damage on it side.
the abilities are % based so the units underneath matter very much so, for the su76 it gets a shot of full 160 damage which can be nice in conjunction with other AT as it will make up for what would otherwise be overkill damage, but on the JP4 it puts its damage to an odd spot that is mostly just absorbed by not changing the TTK, things get even stranger for the su76 when it gets that +20 damage with vet putting it to the unheard of 140 damage, with the first strike bonus bringing it to 175 damage
what's more, while its true the su76 and jp4 have 60 range and shoot at tanks, that about the extent of the comparison capacity. the su76 is multirole for one and drastically cheaper, the durability also dramatically confuses the comparison, we dont compare the puma and the panther despite them both having 50 range and a turret with low AOE on the cannon because unit class matters. durability is the difference between the t34/76 and the kv-1, let alone adding in damage differences and utility like in the su76/jp4 category. the su76 is a baby in terms of AT platforms
another dramatic difference is what the TDs are shooting at, combined with the previous point, makes them very difficult to compare. if the su76 was cloned and put in both okws army and the soviet army, some how set up to hit the field at the EXACT same time, the okw su76 would be better, simply because of the targets it shoots at. comparing things like TDs in a vacuum is difficult enough to begin with, let alone ones that dont even have the standard damage for medium AT in common.
these are the reasons im in favor of a vet rework (bring things like the su76 odd numbers in line, and making the damage bonus of the jp4 mean something) and why i dont believe the 2 units should be directly compared