For those terms I will help with that for you.
“Locked” obviously means locked XD and need to progress further in that girls story to unlock it. It should say how to unlock it.
“Event available” means as it sounds an event is available XD. So for example if you saw Prim’s charisma event said available then when you do her charisma event at evening a new event will trigger.
“Event unavailable” means there is more events but you need to progress further in that character’s main story to unlock them. A notification should show up when you unlock new events.
“Work in progress” means you have seen everything for that event for the current update and wait for more to be added in a future update.