Once you find Romon's notes in the church and read them, head to the base of Lovis' tower. There is a door at ground level (close to the lake teleporter shrine) you will be able to open.
Had you used the scrying stone yourself before giving it to the priest, you would have been teleported to that chamber (meeting a ghost, who you could mindread for a stat point), and when you were done there, exit out the door near the lake shrine.
You can trigger a couple platforms to appear there, with a choice of reward when you are done. The obvious choices are not necessarily the best options.
Lancet's guide lists 'Into Thin Air' in a few places and describes the quest in detail; 'Vault of Anguish' is mentioned once, but split over two lines, so it may not show up in a search ( 'of Anguish' will).
