Your math (and therefore your conclusion) is messed up.
Calculating the accuracy difference against their armor doesn't really work when you are already calculating it into their HP pools. Better calculate it against their effective health (assuming you actually use the correct values) and leave it out of their DPS. For DPS just use the
DPS Spreadsheet because your simplified use of accuracy completely ignores other weapon stats like cooldown and reload (not limited to those, there are many more playing a role).
1.5 armor means bullets have a 66% chance to penetrate. This means they take 50% more shots to kill (33/66=0.5) compared to a unit with 1 armor. This means that the 4 infantry models (320 HP) have an effective health of 480 HP.
Conscripts are 6 models of 80 HP each, which means they have an effective health of 480 HP as well.
You also mentioned manpower drain: Their reinforcement cost per effective HP is exactly the same: 30 per Grenadier, 20 per Conscript. Both are 0.25 MP/eHP. So you certainly aren't on the back foot there either.
Then you factor in their DPS per rifle and number of rifles and they turn out to be roughly equivalent. Of course there are other factors like models dying but to put it bluntly:
Their base performance is the same. Variance is created by randomness, cover and movement accuracy modifiers. If you feel that one side is performing notably worse than the other, then this is either due to wrong use or due to perception (own soldiers lost are more noticeable than enemy soldiers killed).
Of course their performance varies with abilities and upgrades used but the early game unfairness you are complaining against does not exist.
Oh, and veterancy because you're so keen on it?
Vet 2 Conscripts: 576 eHP, 1.78*DPS
Vet 2 Grenadiers: 693 eHP
693/1.78 = 389 eHP -> Vet 2 conscripts are stronger than Vet 2 Grenadiers, assuming no other factors (not complaining, just pointing it out)
Vet 3 Conscripts: 1.25*1.8 armor = 2.25 armor -> 693 eHP, 1.78*DPS
Vet 3 Grenadiers: 693 eHP, 1.78*DPS
On a side note, because you used CoH1 rifles vs. Vet 2 grenadiers as an example: The armor systems of the two games work completely different. One uses the armor and penetration system for nearly everything and the other one used a (to most people) very obscure system of armor types and modifier tables that would vary strongly for each armor type and every weapon. Both have their strengths and weaknesses but trying to explain one system with the other simply doesn't work.