Hello.
This mod launches the Easter event instead of the Halloween event. For example, type "/ runevent HalloweenEvent"

Please check the description. Events are seasonal, Halloween will only work when Halloween is active in Vanilla Rust. We do not have special code to make events happen, just influence when they trigger in game.

Hello. It is therefore the only event that cannot be activated outside the official date.

Server events are only stable and working during the time FacePunch has them active in Vanilla. Outside of those time periods they are usually buggy and broken as they reuse code for these events in other events. They choose to reuse code rather than make the events stand-alone so they can't be run year round.
I use the paid AlphaChristmas Plugin on my server to run Christmas year round. I would personally happily pay to have the other ones too.