More realistic scenario would be one of the Ostwinds flanking T-34 and attacking it's rear armor killing it even faster
Also I have to repeat myself - AT performance of Ostwind is tip of the iceberg, it's performance against infantry is absolutely out of this world especially when you consider it's cost and tier
But if we use rear armor pens to test, two Centaurs will easily kill an Ostheer Panzer IV as well. So that wouldn't prove anything except that players with really bad tank micro might lose their medium tank to two AA tanks? Also the T-34 has higher top speed and higher acceleration so an Ostwind staying behind it long enough to kill it is pretty unlikely.
As it currently stands, the Ostwind is slightly better against medium tanks (unless while moving, then Ostwind is quite bad because it has bad moving accuracy/scatter) while the Centaur is slightly better against light vehicles because of its moving accuracy vs vehicles (100% chance to hit), although it has more trouble keeping up with lights.
Ostwind performance versus infantry (time to kill) is roughly equal to Centaur now, not "out of this world". The Centaur generally has an advantage against units in cover because of the way its gun works (with accuracy rather than with AOE), while the Ostwind has an advantage when enemy squads are clumped up (when AOE is more useful than accuracy). You might want to actually test these things before making random claims.