The question is: Did the elite or at least that kobold mage know that the Khan egg was hidden in the hidden cobby hold? Text: "When Yi’Asan spoke, he pointed the wand at Richter’s face, “You have come into our home and taken something. We will take it back and for our trouble, we will take your heart as well!” All of the kobolds yipped and barked loudly at their leader’s words. Richter squinted at the large kobold. “What if I just gave you the Focus Crystal back? Would you be willing to forgive and forget?” “I am not speaking about a mere crystal and you well know it!” the kobold shouted. “I do not know how you knew to look beneath the crystals for what had long been lost, but you will tell me before you die!” Richter looked about, honestly confused. “If you don’t want the Focus Crystal, then what do you want?” His Night Vision picked up a glimmer of movement. “Enough games, human! If you do not wish to speak the truth now, then we will take you back to the tunnels. We shall see how resistant you are after the burrowing worms begin to nest within you!”" book 3 Options: Yes: They knew, that is how they knew Richtær took it. They want to know how Richtær knew about it and where to look. It was made lost or hidden on purpose. No: they didn't know where the egg was hidden but received a prompt that it was found and taken. They want to know how Richtær knew about it and where to look, as they did not. It was actually lost to everyone. Ramifications?
That is one good hiding spot since the crystal garden has only been covering it for a little over 50 years. A fairly recent hiding spot. “Focus Crystals, and the gardens they create, gain power the older they are. This garden is more than fifty years old, master, and it fills several caves,” En’fota answered. Book 3
Or the crystal guardian was harvested for the special crystal and the garden replanted? Could also be a simple flaw in Aleron's logic.
I think that they discovered the Egg was there due to the Sygil/Symbol that was under the Box that Richter saw after he emptied out the Hidden Alcove, I suspect that whatever it meant informed the Kobold Battle Mage that a Khan Egg had been hidden there. Till then they had not known it was there, the knowledge of it being hidden there long since lost, probably by the hiders being killed after they hid it from the Kobolds that led the rebellion against and slaughter of the old Khans.