Don't you dare nerf Sturmpioneer survivability unless Volks actually get proper damage output simultaneously... that's all I've got to say about that.
Right now, OKW infantry power is lopsided blatantly towards Sturmpioneers, but that isn't unbalanced, because Volks are trash. Can't just go nerfing Sturms based on other changes happening to resource costs and such.
That is simply not correct. Volks are only 'weak' until T1 or T2 is built. Then they have their StG44 and Fire Nades which will make them win every engagement from mid to close while being in green cover.
Volks (and Grens) are not a rushing unit, if you try to storm an enemy position, they will lose. This is intended.
If you play against OKW, you will see that Volks are a pain in the ass because they get incredibly strong the longer the game goes. In the first minutes, Vet0 Volks are a piece of cake. But fighting against Vet5 Stg44 Volks is something that can be really frustrating.
Also as Allies, Sturmpioneers are cancer, honestly. You have to make a 'lucky shot' and let them drop at least 1 (better 2) model(s) when they are closing in in the early game, otherwise you have to immediately retreat in order to prevent a squad wipe.