I think the thing to remember is that the registration information is based on the hybridizer and where the hybridizer created the plant. It's known that plants will rebloom more easily or more often in places where it's warmer and there is a longer growing season. If I hybridize a plant in Northern Illinois, and it doesn't rebloom here, that doesn't mean if I gave it to someone in Charlotte that it wouldn't rebloom there, and maybe grow 5 inches taller to boot. Unless the plant is hybridized near your location, you have to take that into account when you read the registered information. It might not apply to you at all.
Would be cool if, before you registered the plant, you could give peices of it to AHS test gardens in different conditions, so "certified" registration data could be determined by qualified, trained testers that would be consistent and the data would be relevent for different zones/conditions. But what are the odds of that ever happening?