You don't believe you have a torque problem you have a balance issue Those are vibration cracks. I have seen two cracked like that and both were the wrong converter for the crank that was used. The owners racing the car never felt the vibration blaming open headers. What engine are you running ? Is it internal or external balance.
We also just had a 440 race engine 10 second truck. After 2 week ends it had metal in the oil. They pulled the engine and the thrust bearing was destroyed. The crank was shot and it cracked the block up through the mains.
They checked everything the engine came from our shop. When taking the flex plate off they saw a crack. They put the converter in the lathe and found the hub was welded on crooked. It had a 5/8 wobble at the ring gear .
I am sure that is a vibration crack. From out of balance or bent part. Was it ever on another engine where you could have missed seeing the crack starting? Or was it new for that engine?