No engine restrictions by Italy. However, the transmission elements of the helicopter are purchased from Italy and they are adapted to the USA engine.
If you are going to install a new engine, it means you will get permission for a new transmission from Italy. If you say that you will use my own transmission, you have two options: a) Agreement with Italy. b) You do not agree and Italy will sue you in the international court.
Also, remember, even if an agreement is made with Italy, the compatibility of the new engine and new transmission will take a lot of time and money. And the T129 contract expires in 2028. It's not worth it.
Instead, "Let's design and manufacture the Gökbey Helicopter with new domestic engine and new domestic transmission. In this way, the necessary infrastructure for the T625 will be established." they said.