Utomo is from the Sosarian Lands of the Feudal Lords
Utoma claims to be from an island. There is no obvious island culture in Britannia, so it's possible Utoma is from Sosaria before it became Britannia, and is from Lands of the Feudal Lords, or what would be known as the Tokuno Islands. Or, Utomo is from another world such as the world of Moebius and Windwalker. Britannia is a multiversal nexus point
The Guardian becomes interested in Britannia because it attracts otherworldly travelers. Books describe The Caverns of Freitag where Gertan is from, Knights of Legend describes the world where Seggalion is from, and there are descriptions of the games Tangled Tales and the Moebius sequel Windwalker. The Avatar's Earth, and the Ultima Underworld II worlds are all prime real estate for an aspiring multiversal conqueror. The dungeons and the Stygian Abyss are always changing due to earthquakes
Inconsistencies in the dungeon layouts and the Stygian Abyss are due to earthquakes reshaping the land, as well as renovation attempts. The Stygian Abyss in Ultima Underworld is not a contradiction so much as an unexplored series of catacombs made accessible via underground earthquakes. Captain Johne was exploring Hythloth, connected to the Stygian Abyss and the Gargoyle underworld. The Ultima Online map of the Gargoyle underworld is accurate
In Ultima Online, the land of the Gargoyles includes the Ultima VI layout and expands the area quite a bit. This could be an unrevealed part of the land that is present in the main Britannia.Forge of Virtue takes place before Ultima VI
Either on the main timeline or on an alternate timeline, Forge of Virtue I & II take place before Ultima VI, due to Quenton being alive and the events of Skara Brae not happening yet. Not only did The Avatar face the Black Knight twice during this time, but ping pong was a regular activity. Worlds of Ultima takes place after Ultima VI
The Avatar does not leave Britannia for Earth, but stays in Britannia and ends up on a series of Worlds of Ultima adventures before returning to Britannia or Earth. Nystul or the Time Lord may have arranged this by offering the Avatar, the Avatar's companions, and some Britannian citizens to cross through a portal, though they ended up being translated as inhabitants of those worlds until the Avatar returned to Britannia or they were brought back.- The Avatar is on Earth, not Britannia, at the beginning of both Worlds of Ultima games.
