I just wanted to add something on this topic.
I noticed that the Event (“Defend Mad Mardine’s cows from harpies while he tests his invention”) itself is still bugged and will now break almost instantly after a server restart (all 4 servers I checked via the guesting feature were bugged).
I witnessed the event breaking after the first cow which triggers the event should be launched. But instead of launching nothing happened. All the cows are still standing around the cattlepult, you can’t interact with Mad Mardine and Tigh Snatchskull started to circle the cattlepult and tells you that Mad Mardine is testing his cattlepult (if you interact with him).
So basically the event is still broken BUT for me the cattlepult was usable to get to the vista. Not sure if this applies for every server when the event bugs (see dagrdagaz’s post).