It is indeed located in the World of The Lost Lands. The Quail Valley is located in the Green Mountains range, which is located Due North of Martyn's Nest (on the Coast of the Cresent Sea) and the Duchy of Westmarch; Due East of the Westwood; Due South of Sternwood and The Frontier; and Due West of Quintas and the designation for The Grand Duchy of Reme.
Attached is a snippet of the new world map available on the store and the location as described above. You will also be able to see the starting location for an adventure, locate on the world map, and interact with all the points of interest on the map as well with our upcoming World Anvil project. Our public live demonstration and Q&A will be on Feb 2 at 9amPST (UTC -8)/5pm (UTC 0). The link to the demo will be provided in our discord server which you can get to from the main FGG site (scroll to the bottom, grey box with discord logo and our name).
Non pote non sapere qui se stultum intellegit.