To be fair that page is a blog post of the announcement of Greater Big Bend earning their endorsement and has a date published of April 2nd, 2022. The new site received certification on March 11th, 2024.
As an advocacy group they can't force places to apply, and in fact they state that they work on nominations to decide which places to work on. The idea being that if a community cares enough about preserving the night sky that they will be more committed to make any necessary changes to receive the designation.
There's a lot of requirements of the core area and the surrounding areas to do outreach and to preserve the dark sky. Every stakeholder needs to be committed. This includes changing of local ordinances, especially ones for outdoor lighting. Of course, the preserve would be useless if there was no public access allowed.
Hopefully the RAC find value in this and decide to put Jasper up for designation on top of their own. Just because a site has not been designated does not mean that it does not meet its requirements. Dark Sky International isn't saying that Jasper is not a dark sky preserve by not having them designated, it's likely as simple as no one has bothered to apply yet, or if they have applied, the process has not yet completed. Another possibility is they have applied, but were unable or unwilling to make the changes necessary to meet the requirements set out by Dark Sky International.
From a brief reading of their process https://ancillary-proxy.atarimworker.io?url=https%3A%2F%2Fdarksky.org%2Fwhat-we-do... it seems that they take it quit seriously that the proper stake holders are involved, that they meet the standards. Seems to typically require 80% of land owners to participate. They also must show that it is legally protected. This is MUCH different than designating an area simply by how dark they sky is, it is designating that the area is LEGALLY protected to preserve the dark sky.
Not knowing more about Jasper, or the RAC's requirements, and whether or not they have sought designation from Dark Sky International or not, it is hard to say.