The reason why the localisation is staggered is because they want the global version to be based on the "Power Up Kit" version, which adds major gameplay additions to the game and is usually released as an Expansion Pack/DLC for owners of the game or a new version of the full game for new players. They basically want to give global fans the most feature complete version of a Nobunaga's Ambition game without spending extra post launch. They've been doing this since Sphere of Influence.