Ok, my impression of the Fw 189 is a tough, maneuverable, medium-low speed aircraft with a lot glass and the ability to loiter for decent periods over the frontlines. I think the Fw 189 or something like the Fw 189 could have easily served in Korea and in all the cold war conflicts afterwards not really being replaced until the rise of the drones.
Going out on the a limb, but is it fair to say that a Fw 189 was as good or better than late 60s aircraft like the Cessna O-2 Skymaster? Anyway might get taken to task for that, but both the O-2 and Fw 189 had the same mission. Other than the twin tail boom and greenhouse fuselage, I don't see the Su-12 as functionally different than a Tu-2 with more glass. Imagine taking the Fw 189 Argus engines, replacing them with BMW 801s, scaling up the twin-booms and wings, streamlining the Fw 189 forward fuselage to look like a Ju-188 or Ju-388 and you have the German version of the Su-12. Cool plane, but don't think it could perform the same role as a Fw 189.