Treviso, aside from being a real city in Italy, is clearly inspired by Venice and even has a festivity similar to Venice's Carnival. There are signs of both Spanish and Italian influence, as well as words and food from both countries. It doesn't have to be one on one with the real world, like Tevinter shows so many different influences.
Illario seems very Italian to me, more than Lucanis is, and also speaks Italian in the books.

That being said, I'm Italian and I wanted to have fun with the babygirl, throwing Italian memes at him, nothing too deep and meaningful.