The Seer won't be able to resist the trapped ring; we just need to find out where the harp is.
Gwinnling was preparing for this, way back in chapter 1; it may be worth looking at his notes again.
The 'painting' on the far side of the attic has some words scrawled on to it, but Geron can't read them.
The problem is apparently how small the words are; try looking for something that can magnify them.
The scholar was surrounded by books and has been reading them for several days; he probably has something useful.
Take the magnifying glass from the table next to the fairy scholar, then use it to read Gwinnling's writing.
The name it reveals needs to be studied in the library.
Gwinnling's notes mentioned 'Raven's Peak' - that sounds like a place.
Check the Geographia section.'
You've learned the location of Raven's Peak - you could read the other books in the library, but can depart whenever you're ready.
Speak to the fairy scholar about your departure.