At the bottom left of the world map there is a section for green checkmarks for world quests. I don’t remember what they’re called. Where do ya go to turn that in for the cache? In BfA.
When you complete all 4 check marks you should get a quest to turn in for the reward. I’ve only done a couple on the Horde side so I don’t know where all the turn-ins are. The ones I vaguely remember are (I think) Zul’jan Ruins for Talanji’s Expedition and Goldtusk Inn for Voldunai. Champions of Azeroth you turn in to Magni just outside the Chamber of the Heart.
Thank you; appreciate it.