Well, you said originally, that it would let me know if I complete the tomb. And I was doing a few of the early adventures in the Pyramid of the Burning Sands, and it said I had completed the tomb, yet there was still a few undiscovered rooms.
And according to the adventurer journal, it says it was a completed tomb.
There was also a side corridor that required a moon fragment which isn't tied to an adventure(it even gives you the key in a chest to go through it), and it too said it was completed. On top of it, if you have the "Fully explore a Tomb" wish, it gets fulfilled when you're alerted you completed a tomb.
So... I'm just going to go with this, and hope this is how you fulfill the wish.