Since the event is both random and buggy that leads to the Cattlepult in Diessa Plateau being accessible so one can visit the vista on top of the tower, why not remove the trigger and make the cattlepult always able to be accessed by players to get to the vista?
It’s one thing to require a quest that be can be done any time as a pre-req to access things (like completing a heart for example) but another to make things like skill points/vistas needed for zone completion to be tied to a short interval of access after an event that begins randomly and might get bugged out preventing completion… so until events become stabilized, why not remove the trigger entirely for this vista and allow players to access it at any time?