If placed in the game, Rock Crick hunters will talk about hunting yao guai with each other, and if spoken to by the player will eventually mention that "there's a 'Guai den to the north." Which area they are referring to is not specified beyond this.
Their editor IDs (FFDRockCreekHunter01, FFDRockCreekHunter02, and FFDRockCreekHunter04 through FFDRockCreekHunter07) suggest that they may have been intended to be associated with Rock Creek Caverns in some way.
Additionally, the above Editor IDs appear together in a Form List (FFDCRockCreekHuntersLIST) whose only other entry is for Grandma Sparkle. This likely indicates that these are her "boys" who are out "hunting 'lurks" before being cut from the game, with Grandma Sparkle's dialogue the only remaining bit.