The coordinates for this quest aren't wrong :D Or at least, the way I entered them isn't wrong.. The way they're interpreted might come across as wrong.
Where Y'shtola is standing when she gives you this quest is at X7-Y8 inside IDYLLSHIRE (not Matoya's Cave.. The quest is to go find the Cave, how can she give out the quest to find the cave inside the cave?)
Where she's standing for the first part of the objective is at (13-36) inside the Ruling Quarter in the Dravanian Hinterlands (which we definitely need to show a little better, but its listed on her npc page http://ffxiv.gamerescape.com/w... )