>>56076487The blurbs seem to have existed as far back as 2010 according to archives. Trying to find any info off the official English sites when these sets were relevant is a pain thanks to the site during Gens 3 - 5 being riddled with Flash.
I've also found more rumors like how early versions of the Bulbapedia article thinks that Holon is located north of Kanto, Mirage Forest was mistranslated as Eidolon Forest, the crystals in Crystal Guardians causing the Pokémon to become Delta Species rather than the reverse or left mysterious, and the assumed relation between Holon and Mew going as far back to when the sets were recent.
More links of interest.
2008 thread from the PokéBeach Forums that also tried to gather as much lore info as possible. Contains lots of speculative rumors and incorrect info. (Tracking Mew? Holon Lake has marshes? No floating island.)
https://www.pokebeach.com/forums/threads/the-holon-and-delta-stories.36295/2020 article from a JP TCG fan blog about Pokémon Star during the Delta Species era. Mentions that Holon is not a region and that the changed types of the 3 Pokémon Star that are Delta Species matches their colors.
https://ameblo.jp/cardshopathomemiyazaki/entry-12590769538.htmlPokémon USA press release for Holon Phantoms, Crystal Guardians, and Dragon Frontiers, archived on Pojo. Mentions that Holon Lake is nestled deep in a forest south of Holon city and that Dragon Pokémon rule the islands set in Dragon Frontiers.
https://www.pojo.com/pokemon/news/2006/3-3.shtmlhttps://www.pojo.com/pokemon/news/2006/8-24.shtmlhttps://www.pojo.com/pokemon/news/2006/2006-NewsArchive-Sept.shtml