Blue
Ravenous Bugblatter Beast of Traal
I couldn't find anything on the Wizard's site, so I took my information from wikipedia: Dungeons & Dragons campaign settings - WikipediaJeff Grubb made several statements both in Dragon Magazine, as well as in two 2nd edition FR products that 2e was THE home of FR (not just "A" home, but "THE" home).
Admittedly, that can be taken a couple of different ways.
Regardless...
The most compelling statement comes from Dragon magazine issue #153 (January 1990) in the article "The Game Wizards":
Under the FR listing, it is listed as official only for 5e - but on closer inspection article does not list AD&D nor AD&D 2ed. With those Jeff Grubb sources you may want to update the Wikipedia article and preserve that knowledge.
However, the point under discussion was basically if the FR setting changes with edition meant that as a whole D&D always had changes to their official setting with edition. Basically, is setting change mandated by D&D edition change - must the setting have a timeline and the meta advance between bookmarks of edition changes. They were using FR as proof, and simply there were edition changes where the official setting had no timeline advancement. That FR was official for two of them instead of one is of interest, but doesn't really change the point.
Do you know what the official setting was for AD&D? That would be useful to update that wikipedia article.