Flexplate is not fits the torque converter

Mike I think you misread his meaning. But you are correct. Achill, you appear to indeed have an "unbalanced" engine...that is it requires EXTERNAL WEIGHTS. That is why they are called "externally balanced" You must have WEIGHTED front balancer and weighted converter or flex plate to cause the engine to be in balance.

But looks like I have weighted converter? (Balanced - YES)