I think that is a bit hard. What happened was a difference in
interpretation...

It was a bit hard, and I apologize. We agree on what happened.

I acknowlege that it has always been possible for a national
record to exceed a world record due to a difference in
interpretation of the rules. The Jim Payne example is a case in
point.

However, I think that you have missed the distinction between
the Jim Payne reality and the following hypothetical:

What if: a pilot who already holds a world record uses the same
flight recorder on a flight that beats the old record. He
submits his claim, gets a new national record, but is not
allowed to claim a new world record because the flight recorder
was downgraded in the meantime.

This is not a matter of "interpretation," nor has it ever
existed before. It is merely bizarre.