I'd like to make sure I get all the achievements (and mounts of course) before they disappear, however, this is the first ever event that did not have an original end date set, or have an event page, or have their achievements listed in the seasonal section only once they're complete... This leads me to wonder if it is permanent.

I ask for reasons of time management - if it is temporary, I need to get the rest of my jobs up to 60 in order to get those achievements. If it's permanent it is no rush.