I believe the 3/6 fixes indicate that the version uploaded here (by the way, thanks once more mikufanboy!) has some bugs.
At a glance, the kissing doesn't work for me (as reported by another user). You can trigger it with some NPCs, including the grey haired fairy, Vivi, the archer girl… you need to be relatively close. But all you get is some dialogue, which seems to be the girl stating that she suddenly finds Airi really hot, and then you get a sprite of the girl you kissed standing still until you "break free", seems the kiss animation is glitched. If the "magical costume" indication is correct, maybe Gun Airi can kiss? I'll give it a shot when I can.
The gun airi costume also has some control issues that pop up at random.
Edit: Confirmed, the kiss animations seem to work as Gun Airi. At least Noir, the one I tested.