Remember back when Blind Mew released the first letter of the next skyway? C? Yeah, people came up with Cádiz, but as a matter of fact, on Earth, Calabria is 1,134 times bigger than Cádiz. Perhaps Cádiz is only an island within Calabria or some other skyway. But, still, Cádiz is confirmed.

"Yes, I can read this. It is a simple code the Armada favors. I see the books you are looking for. It seems they have been sent on to Cadiz."

"Cadiz? Let the books go, captain. Sneaking here was bold but Cadiz is the center of Kane's power. Going there is suicide."

"You will surrender and be taken prisoner to Cadiz. If you do not comply, you will be destroyed. These are your only options. What is your answer?"

Oh, I guess they don't use the accent on the 'á'.
Those are the 3 Cadiz-related dialogues I know in the game. There might be more. Anyway, Cadiz is confirmed, but not necessarily as a skyway. Goodbye, have fun with your wizard game.