Ceril VII is Kulthea, the Shadow World. It's indicated in the SW Master Atlas III, p 178, under the entry of Third Era year 6020. The only thing odd is that it is indicated that the orbital station is set up by the Imperium, House Colos and the Dia Khovaria - even though it is part of House Devon space and 'Imperial Crisis' states that the small orbital station is controlled by Devonians. It looks a bit like a mixup there.
It must be noted that this entry was absent from the SW MA IV.
Another entry is present in Emer II, in 6023 TEI : "Terran Empire: [TARA agents (a division of the Dia Khovaria; the ‘TAbernacle Research Agency’) violate Terran Empire quarantine and land on Kulthea, in Námar-Tol. Concealing their true identities, they make contact with a select few Loari Elves in Námar-Tol."
Yet another entry in Emer III, post-6053 TEI : 'In orbit, the Imperial observation station picks up the disruptions in the global energy barrier. The Dia Khovaria dispatches a support ship, which lands safely on the uninhabited Tower Isle in SE Emer. They set up a base and from there they try to contact the first group sent thirty years earlier, and the small team sent just two years before; Patrick O’Kiran is among the crew of that more recent ship.]
In Emer III, there is an interesting bit of fluff text as an introduction to part XI 'maps and charts' :
"Dia Khovaria Datafile: Delta 93218
ImpDate: 475.097.12.02 Imperial Standard Time
To: Father Belthus Rekan, Administrator, Church Orbital Station and TBD relay #267
From: Patrick O’Kiran. TARA Agent Rank 5
Status: Classified: Level V Signet Seal
Planet: Ceril VII (native local name: Kulthea)
Subject: Landing shuttle mission to planet surface
Mission: Secure advanced ancient harbinger race technology for DK exploitation; determine nature of planetary energy barrier
Message: Reverend Father: I am currently aboard a native ocean-going vessel, approximately 5000 kilometers ENE from the landing site/base camp. My immediate destination is a region in the southeast of the continent known as Emer, where I have detected very unusual electromagnetic resonance readings on long-range sensors. Agent Kraus remained at the previous port to follow up on a related energy reading. As before, communication is intermittent, though handheld devices continue to function locally within acceptable limits.
In Your Service by the Word,
Patrick O’Kiran"
There is actually a temple of the Church of the Word in Haalkitaine, with the following information : "GM Note: The Church of the Word is actually the Dia Khovaria, an organization in the Terran Galactic Empire, one of several factions with covert operatives on Kulthea. All are seeking ancient tech artifacts, and to unlock the secret of the Essænce: the strange powers controlled by residents of this technologically
backward planet."
It is quite explicit that what is disrupting Terran tech is the Essaence.