Well this is a hell of a delayed reply, I have no idea how to subscribe to threads here if it's even a function :P
Credit's fine, I've done quite a lot of research for this game now. As far as an all characters checklist goes, well... I kind of made an autosplitter so you may want to contribute to that if you have ideas.
Thanks a lot for finding the memory, that let me debug it.
It's solved, the trigger for the counter incrementing is actually to touch a slightly more specific point / smaller hitbox (I think it's lemeza's hitbox intersecting with the centre of the fairy point) than is required to summon a fairy, so if you turn around or warp out after barely touching a point it won't count despite the animation and fairy being summoned. Also fairy points count towards this even when you have another fairy out.