They have stated that they didn't change the engine... At least not yet. They just try to port it and try to adapt stuffs to the lastest version of Unreal Engine 4. In order to jump the engine they will have to take more times to research and study as Unreal Engine 5 is limited to a lot of new techs and issues that 4 doesn't have. At least like maybe in another 5 years we will see they considered thoughfully about Unreal 5maybe another project will go in dark this game has so mutch potential but the change of the
engine will take maybe a year or more ! another scammer maybe ?