[2020] Are all events once a year like holidays?

@Enneth if you have only just done this deletion, please raise a support ticket.
On another note it could have been far worse you may have deleted a Fire Phoenix or a Brown Bear instead.  

I personally am a hoarder in Elvenar. With a very full inventory as I don't part with anything much, especially when it comes to event buildings and artifacts. I figure the few minutes it takes to trawl through is nothing compared to the regret of getting rid of something I should have clung on to.