Hey, I'm new here so forgive me if I don't do quotes properly!. I'm just posting as I see the idea that Urithiru may have been in the skies above the Shattered Plains has been bandied about. This can't be the case as the epigraph at the start of chapter 35 reads:
'Though many wished Urithiru to be built in Alethela, it was obvious that it could not be. And so it was that we asked for it to be placed westward, in the place nearest to Honor'
As the Shattered Plains are at the far eastern side of the continent, Urithiru wasn't there. My guess is that perhaps it was near Shinovar, perhaps in the mountain range there. I'm quite prepared to hear that I'm guessing wrong though!
On a separate note, the reading about Shallan has me properly confused, I have no theories whatsoever about it, just lots and lots of questions!