The cave of "Yenidan", north of Helnim is empty except for a single hostile orc and some bloatspore. The orc "TR_m2_O_Garstal gro-Azg" doesn't appear to be related to any quests (a text search returned nothing).

The cave itself is mentioned in one line of dialogue for the topic "Assurbalhet" where it's used in directions to elsewhere.