I am a big believer in breeding locale specific whenever possible. the reasons are simply for the enjoyment derived from seeing offspring that theoretically could be, or at least look like animals that are out in the wild and may never otherwise be seen during our lifetime. Loose attachment of a locale is misleading and doesn't really add big dollars to a snakes value anyway.
In my opinion Locality is only going to be important to as many generations as you can trace back to wild caught ancestors. There is nothing wrong with refering to your snakes as river road alternas, but you should be upfront as to the details of how locale specific the animals are.
For a relevent example I have 2 locales I am working with, Juno Rd. and 277. As for the 277 locale, collected a female 3.5 miles north of Loma Alta, and I collected a male 1.4 miles north of loma Alta. I know with 100% certainty the locale of the parents of any offspring, and I would represent them to anyone as F1 277 north of Loma offspring. The fact that I (or any human for that matter) decided that those two exact snakes should breed this year is not a natural pairing, and the offspring are technically "man made" anyway, but are as legit on the locality description as you can get.
The Juno locale pairing I have is made up of a female I personally collected in the "S curves" south of Baker's crossing. However I have a similar situation with My juno male as you described. I purchased the male in at a show in Orlando FL. The guy I bought it from sold it as a lone male yearling marked "Juno Road" the details he provided to me verbally were that it was produced by and purchased from Seven Generations Reptiles of California. I was unable to contact the breeder to verify the animal's origin(I believe they have since gone out of business) the offspring are Juno Rd., but with that description attached.
ofcourse the best case scenario for captive bred or captive born locality animals is to collect a breeding pair in the wild, "caught in the act" and to produce in quantity, offspring from that naturally occuring pairing - this is very rare, assuming it has actually been done.
the bottom line is that if a grayband is to be called a locality animal, the lineage of that animal should ideally trace back to wild caught ancestors. if it cannot be traced back with certainty, I would regard the locality name attached to the animal as helpful, probably accurate, but not precise, and appreciate the beauty of the snake regardless.
Jim
oh, P.S. I really hate hybids in graybands, maybe someday when collecting in Mexico is commonplace and the hybrids look like som naturally occuring integrade, but whenever I see a grayband with a little ruthveni in it it's like nails on a chalkboard to me!