How do I make it where when a focus is completed a country will get an event about another country wishing to join their faction?

I'm assuming the event is: sorcerer-kingdom-events.1

For that you would do:

TAG = {

country_event = {

id = sorcerer-kingdom-events.1

days = 1

}

}

Replacing TAG with the tag of the nation you want to get the event.

Also, in the event, remove the content from the "Trigger" box, as it will conflict with "Is triggered only" and the event will never fire.