I remember being in GTA San Andreas myths growing up and seeing the same conversation about game files. Some myth hunters proposed that the game files associated with the myhts were encrypted or some sort of "ghost files". I think the "ghost files" hypothesis is a bit too far fetched for MM6, esp given the age of the game.

I originally saw the white goblin myth here: https://www.angelfire.com/ns/flute/spoilers.html

It involves the flute in the Dragoon's caverns, the NS buoy resetting the zone (????), the Kriegspire drakes, the so-called "Grey Magic" skill and a NWC-esque dungeon who has all the spells for Grey Magic.

Here is another thread about the white goblin in this forum dating back in 2008. https://telp.org/mm6/tavern/anyboard/posts/39427.html

I also downloaded some tools for the MM6 assets and likewise saw no assets relating to any white goblin or grey magic.

IDK but video game myth hunting brings up some of the strangest ideas in people's minds. If you want a chuckle, i suggest checking LeatherIceCream's series on GTA Myths. It's hilarious.