I have thought about Farhaven a bit and right now my plan is to place it in Ag48. The background would be that the Wyrm-believing refugees of Falender tried to reach Alderland by sea, but when they understood that it was impossible they settled as close as possible. The location is also very close to Solehaven, where the humans originally should have entered the lands (according to the history presented in the Gamemaster's guide). I guess that suitable legends to place in the library could be the ones of Nekhaka, Ivelde, the Phantom daggers and Wyrm's key.
I really like your idea, although I did it a little bit differently. I placed Farhaven in An21. The coast of the bay spans over three hexagons, so there is plenty of room for my players to discover arround Farhaven
Some time ago I found this awesome adventure-site artist and always wanted to use it for my adventures (I think I already posted it somwhere else in the forum)
I used the biggest city of the map as Farhaven. During the Alder Wars, minor nobles were sent to the bay along with their people to colonize the area and build a port for the fleet of Alderland. But with the never ending wars and much more bigger demon problems, the King of Alderland stopped to support the colonization, so the people of the bay were on their own.
Today we have several tiny villages along the coast and after Falender was burned down, the church of Wyrm settled here too. A few weeks ago, smugglers found a passage to Alderland and are now smuggling people and goods along the route.
In Farhaven I placed a large monastery of Wyrm, a big temple and the library, which is a big, fireproof cuboid. The head of the curch of Wyrm is also located here. He wears Wyrm's Key (which is also the key to the library) around his neck.
I used a lot of the PDF's I bought from Roan Studio on DriveThruRPG. If anyone is interested, I can't recommend the Bay of Spirits PDF enough