Thank you, Thijs, for pointing out the problem with XHansara and providing your other observations, which I will try to address. Please let me know if I've missed something.
You are absolutely right about XHansara, described as a cross of Agave, Mandreda, and Polianthes. The species of the latter two genera have been reclassified as Agave species, so I've edited the entry to show the genus as Agave and to add XHansara 'Jumping Jacks' as an also-sold-as name.
This happens when species are reclassified as synonyms for other species and we are always grateful when we are informed of this and we are eager to edit the entries accordingly. If you can find intergeneric hybrids that have become intrageneric hybrids, please let us know.
As for the cultivar entries for variegated plants and other cultivars such as Agave victoriaea-reginae 'Compacta,' these will not be found in the CoL because the CoL does not list cultivars.
The hybrid taxa that are not included in the CoL or our database are hybrids that do not occur spontaneously in the wild. There are several reasons that hybrid taxa are not listed. One is the error you pointed out in the XHansara genus. Even some spontaneous hybrids were once listed but are no longer listed. One popular hybrid taxon, Spiraea x bumalda, is no longer listed in the CoL and no longer warrants an entry in our database even though it is still commonly used by nurseries. It was originally listed because it was a spontaneous hybrid of S. albiflora and S. japonica, but S. albiflora is now a synonym for S. japonica.
The "man-made" hybrids are not listed as hybrid taxa in the CoL or in our database. In some cases, these names came into being because the hybridizer chose to give the new plant a hybrid taxon for its name instead of giving it a cultivar name. In others, the hybrid taxa have been invented by nurseries for marketing purposes.
I don't know the specific reason that Aloe x spinosissima is not listed in the CoL, but I presume it's because it's not a natural hybrid. Perhaps @Baja_Costero
, the Aloe mod, can answer that question.