The game is definitely set in a New York-ish city. Atelier 54 is a play on Studio 54 (atelier being French for studio), and there's a mention of another school named Galliard that's meant to sound like Julliard.
I've never been to New York City, though, and I don't really have assets to match it besides, so there's no way it'll be represented accurately in the game. So nameless the city will be! 😉