I'm not sure if Toby has ever put 2 and 2 together, but I went through that trans.....I recognize the pics from his sledpulling vids.
Since he has been putting it through it's paces for almost 2 years, I would say the bolts were tight.
I have been looking at the pics and trying to come to a conclusion.....the sleeve(pilot, hub) looks to have a piece that was missing prior to the recent breaks. It seems that the sleeve was the first piece to go and led to the flexplate cracking. If the flexplate would have went first, the converter would have stayed true in the hub as that would have been the only thing keeping it centered as pressure from the trans pushed it forward. You can see the holes are elongated side to side/up and down as opposed to being in a circular motion in which the converter rotates and it has not affected every hole. If the bolts would have come loose first, I beleive we would see signs on every mounting hole in the flexplate in the opposite direction. The sleeve is more crucial in centering the converter, as the same with the dowels in the trans adapt, the bolts just hold it together.
So, if you didn't realize it was me Toby...now you know....so do you need some help here or what? I know you didn't buy the parts from me, but I can still help getting the converter done. Might not be a bad idea to freshen the trans while it's out.