All addons working with Seasonal events should use this library and the addon devs should collaborate and update the lib then. Would make it easier as you do not need to update 10 addons anymore but just the 1 library if any info about events change:
https://www.esoui.com/downloads/info...ntManager.html
Imo this would be the best way to solve this shortcoming of the ingame API for the moment, and it would strip redundant code in all of the similar addons.