So for a project I've got in mind I needed a list of all dead worlds in the FedSuns, so that's just what I've just finished compiling, and I thought that other's might find this useful. Now be warned I used gruese.de website for this, as it gives a map of the IS in 3025(?) using custom, angular borders, probably to make things easier, but with lost/hidden worlds as grey dots, making them somewhat easy to spot, so here's a list of all 177 lost/hidden worlds within the border of the Fedsuns, along it's border with the TC, or just across the border into other realms.
Cork
Roscoff
Duxford
Medron
Wittington
Caerlaverock
Bothwell
Tanatallon
Tatopani
Verdinge
Kublenz
Bayeux
Périgueux
Saumur
Arromanches
Nouveau Toulouse
Swales
Turkalia
Josselin
Chaumont
Carcassonne
Entalun
Ballentine
Courtney
Charleywood
Carnac
Klamriz V
Saltural
Manksville
Lockdale
New Florence
Waycross
Chota
Tallassee
Alnadal
Declan
Sturganos
Messartim
Tedibyhr
Tianamon
Everett
Versailles
Acoma
Arcadia
Angelsey
Westphalia
Anaea
Plataea
Genf
Caria
Lacadon
Boeotia
Aosia
Oli
Vintru
Hurgh
Gahral
Reinhardstein
Gravensteen
Meinhof
Dirk's Gulf
Vecchio
Dol
Ferrara
Mytilene
Paches
Bahl's Retreat
Stockpoll
Branzoll
Noh-wan Hohm
Turko
Nis
Herat
Dunkerque
Skaslien
Fable
Brabent
Knutdor
Khi
Adler
Namen
Smythe
Aggstein
Gruyeres
Nogales
Pula
Helixmar
Blida
Maharet
Laong
Weiz
Jenet
Chillon
El Kerak
Lfe
Oligar
Tetschner
Yongd
Pentvar
Lochmantle
Daol
Dhaulgiri
Chouli
Bodnath
Tazaraki
Crawford
Pietermaritzburg
Hé-shí
Sanurcha
Kautokeino
Blandou
Fathepur
Korvitz
Maison
Lynchburg
Du LacadonUnkador
Saltville
Sinancas
Bornal
Vereemiging
Zambezi
Zacatecoluca
Chirac
Tircuchirappalli
Jacobabad
Dumassas
Ormal
Kaufermann
Teylingen
Andelys
Yamoussoukra
St. Cyr
Hoensbroek
Sumerstide
Rennes
Kenilworth
Frankson
Fugeres
Former Taurian Worlds
Traussin
Mavegh
Zakzangor
Werfer
Merlin
Desolate Plains
Victralla
Sartu
Hanseta
Outback Border Group
Giverny
Gamlestolen
Mackolla
Arundel
Bambrugh
Batrock
Valois
Ulvskollen
Merowinger
DC Border
Pokhara
Oldsmith
CC Border
New Stevens
Conwy
Undra
Kelk
Staffin
Alto
Dowles
Bhykov
Zindao
Patan
Bogerth
Yán-hí
Belamor
Zanzor
Braum
Gardnaus
Weitinger
Maldive
Non Diz