Pgrens can be out in about 3-4 minutes. T70 isn't going to last long against a faust or Shreks. Even a scout car cannon can clean it up from the rear.
The fact that the FLAKpanzer can go toe to toe with a T34 is also laughable. Ostwin is so ridiculously good against infantry/AT guns and also has FREE anti-air. It shouldn't be able to penetrate a T34, which was one of the best tanks of the war.
The Ostwind has a 37mm auto-cannon. If it were firing armor piercing shells, it could most certainly penetrate the armor of the T-34/76. The Germans were relying on PZIII with 37mm and 50mm main guns up until late 1942 when the 75mm L/43 variants of the PZIV started seeing service.
Even though the T-34 greatly outnumbered them, they still managed to knock out 2,300 T-34's in 1941 and a further 6,600 in 1942.
It is certainly possible for the Ostwind's main gun to damage a T-34. The question is whether or not it carried any of the right type of ammunition to do so.