In an interview with 4Gamer, Hamaguchi said that the team had already adapted UE4 for the Final Fantasy VII Remake series. Instead of switching to UE5, the developers decided to use familiar tools to release the game faster. He believes this is the best decision from a business perspective and for players.
Hamaguchi noted that even at an early stage of development, he decided to continue working on UE4. This was the right choice, as the team could independently refine the engine for their tasks.
The developer stated that for Final Fantasy VII Rebirth, the studio created its own rendering system, comparable in capabilities to Nanite technology from UE5.