Is this a bug or am I missing something?
My task is "Travel to the Astryl's Vale Region".
I click on the region. I click on Ethernia. I get sent to The Howling Pass.
If I go to the url: https://www.sylestia.com/explore/town/?town=ethernia I do see the city, but I came up with that url myself and I don't think it's the way to go. Plus, I still can't do anything there, the story doesn't progress.

I don't know how to continue the storyline anymore. Should I wait untill after the event?

Ethernia and Astryl's Vale are part of the same 'map' system as the festival zone. You can only be 'in' one map at a time. Accordingly, you'll need to click on 'Exit Zone' while in the Howling Pass in order to then travel to Ethernia and Astryl's Vale.

Similarly, once you're done you'll need to exit Ethernia and Astryl's Vale in order to reenter the festival zone.