Actually yes it is hard to miss given that there are no signs that you need to do anything but look at the schedule, see the missing event, and be there at the right time in order to advance that event. This is how virtually all the other events work: You repeat the events and when you see a new option you go for it and advance the event.
This is why the hint system needs to indicate that you need to do something new and unusual otherwise the player has no reason to deviate from the normal gameplay that the rest of the game has operated on.
This is a poorly thought out game design decision at its core.
Actually there are signs that you have to talk to the characters, otherwise how would you get the pictures? Arrange the special events, etc?
Just because the player gets into a loop and ignores alternate selections that are in the game doesn't make the design poor, especially if the design was sucessfully used in other parts of the game for a similar purpose.
As for me, the meeting with Adrinanna trriggered from Natasha, when I choose to talk to her for a different item. I don't know if Katherine could also trigger the talk, but I don't see why not. The player is the one who, in all games, needs to try something new if they get stuck in a loop from doing the same actions over and over.