I was randomly able to skip the task with UI cheats (I've been trying that for the past hour and now all of a sudden it worked). To be clear though, when I got stuck there I did the folder rename thing and created a fresh and clean save on an untouched new game. The task told me to call the Envoy, but the Envoy did simply not exist with no way for me to summon her.
Edit: After getting the "Call the Envoy" task for the second time and it again being impossible to call her, I restarted my game, and was again able to progress the quest using UI Cheats. So I'm guessing that is a workaround for this specific issue, just that at least for me I have to restart my game before UI Cheats actually works on the event UI.