If more girls are added for night adventure it would definitely feel more rewarding if it had a slow progression similar to the beginning of the game. Like the same mechanism with slight changes to the minigame, reactions and interactions (not repeating same things already possible with Yuna) to make it interesting. It's just a suggestion but it would be pretty possible if the story is told from another guys perspective who randomly got the magical camera as well.
And to be honest, night adventure is the main plot of the game so other kind of updates such as adding a few more random scenes or pretty much anything would feel less significant even though it would be great and definitely should be done.