Definitely needs more of the chests. I've never even bothered to try for them because there's 1-2 people almost always on doing them. You could even add them to the various overland ruins, inside Zipactriotl, in the villages, etc. With the villages, you'd have to go after them like picking and stealing from chests in NPC towns, where the locals will kill you for looting their precious ancestral artifacts if they see you doing it.
Or, they could add cores to Ter Mur Treasure Maps and loot of the top monsters of Eodon (Shadowguard roof, Myrmidex Queen, Zipactriotl, Dragon Turtle champ, Great Ape and T-Rex).
Or, adding Eodon T-maps where you might get a separate one of these chests as a rare bit of loot in the chest (that will require its own picking).