Alfa Romeo is owned 100% by Fiat; by extension Fiat develops the engines.The 2.0T is an Alfa Romeo design. Fiat did not make the engines. Not all the parts on the Jeep engine are the same as those on the Alfa, but it has proven to be a good design for Alfa.
You can call it an “Alfa Romeo engine” if it makes you feel better, but there’s no escaping that Fiat is the automaker and Alfa Romeo is the division. As such, Fiat sets the development goals, budgets, the manufacturing processes and the standards of quality; Alfa Romeo engineers make it happen within those parameters.