Tried exploring Moss Temple (explored 2 floors twice), and didn't find anything related to a treasure there, although I found a bunch of other items. Came up with nothing trying to explore near Sedimentary Way on the Plenty of Light quest. I think a place to get a hint or two on each of the quests would probably help (even just a link to a document on the general area of where the quest takes place, and maybe some special notes like if it's an object you are after, what does it look like), as most of my trouble comes from just finding where the quest or its objective takes place. You get hints on where you can ask about a particular quest, but after that you're kind of on your own. It doesn't help that in general, I feel the Pokemon encounter rate is a bit too high, so dungeon exploring felt tedious. Other than that and surprise high Pokemon levels on a quest (ran into one where a wild Pokemon was level 40+ and my Pokemon was only level 5), the game is fun.