Hi,
Relief Infantry
in general abilities like "Relif Infantry" would make more sense for Soviet Union wouldn't it? Heavy losses replaced by concripts. That would make indeed sense, but a manpower starving (reallife) Germany having Relif Infantry is wierd. Wouldn't that make sense for the No Retreat No Surrender commandr?
SdKfz 250
It is so fucking expensive, armor is not really there and it does not even have an frontal MG like nondoctrinal units like M3. I would say, give it a armor buff to M3 level and an MG42 facing front (like in CoH1) And i am not talking about reinforcing like OP Quad
Soviet Industry
I like your idea of folding repair station with vehicle crew repair. I think this is a doctrine where the old CoH1 ability would make sense -> Allied War Machinery. You can pump out T34-76 and if you lose them you get replacements. That is Soviet Industry.
Flak Emplacement
Again, make it like in CoH1. It can vet up and is able to hit something. Bofors is so fucking awesome and this emplacement is not hitting the broadside of a barn, just shooting 3meters in front of it into the ground dealing nothing. Would be nice if it could not be sniped and at least effective.
Heat Shells
I think they are nuts. Replace them with Panzergranate 40 APCR? Heat Shells would make sense on long range due to the hollow charge, ingame they are so bad due to the low velocity.
Scavenge Doctrine
What is the Ostwind for? I got a Luchs that i prefer - but that is just me - a Wirbelwind would be another thing...