There has been some recently added functionality to give colors to the events based on tags, but it would be absolutely great if the events post.topic.tags slugs were copied to the calendar events classNames in the addEvent() call, either as slug or as tag-slug. The discourse-post-event/events endpoint already copies the tags to the data structure on the client side.
Since the rendering of the calendar in the calendar plugin is all done in an initializer, it’s hard to override. Is this something you would accept a PR for?