There's one last remaining step to reach perfection - hint for each girl where to look for next event. I don't know how difficult it would be, but I can dream. Never again wandering around and looking for something happen.
This is something I've thought about a bit. The event list pages have a lot of empty space on them, so it wouldn't be difficult to add a single line of text next to each giving some hints (though still pretty time consuming).
But if I were going to do something like this, I'd probably want to do more and have that text change depending on the player's actions. Something like this:
Here, there's no text next to Cotton Candy because the player's already completed it. But they haven't seen Semantics, a Rin event required for the next Niki event, so they're pointed in that direction. Once they've seen that event, the text changes to "Call Niki at night."
Doing that would obviously take a lot more time (and testing to make sure things were working correctly) and, with the guide/wiki out there, I'm not sure if it's worth it (also, the triggers for most events are really straight forward).