Aren't the certifiers looking at the paper work sent in? That is when one measurers a 5k, the measurer uses the shorter of the two measurements and adjust the course to the desired distance.
I have not seen many if any applications for a race of a desired distance to been longer than that distance. I'm not saying that we shouldn't have a limit as to when we call something a specific distance. However, I feel it doesn't happen often enough to create another rule.