Why can elond see the moon letters on thorors map

It is because Elrond knew about the moon letters that the dwarves long ago used. Also the night the Company (the 12 dwarves, Bilbo, and Gandalf) reached Elrond's house was the night the moon that the moon letters were wrote on was that night centuries after. The moon letters were also only readable under that moon.

what is the question here ?