HOW TO TRIGGER ELENI'S ROUTE?!?!?!?! T_T I can't interact with her anywhere beside at class and when lunch
You can trigger her route by interacting with her at class & lunch, do it continuously until you get the dialog "approach" at 08:00 pm and I also recommend you have a moderate or high level of charisma before you go into Eleni's route.
About the charisma thing, you're locked into her route until the day ends, meaning that you need to have that charisma level before you go into the route cuz you can't level up the stats once you enter her route