Well, like you said, the 1997 wipes might not have matched the 1977 wipes to a T--because that example never existed in 1977, technically. The A roll is a new CG shot, so they had to do a new wipe from scatch using a new A roll CG print out and a B roll from the original camera negative. It looks like the difference here is about 4 frames. Deliberate or maybe just a mistake. But its likely because they were not technically re-creating an original cut but working with new material.

What you really need to do is compare 1997 to 2004. Because if I am right then the 1997 versions should basically match 1977, but then 2004 starts early. If 1997 and 2004 are both the same early starts then it would just be that they decided to start each transition a few frames early for some random reason.