I have a fun theory. FTL is similar to LWM in the past, much like how the Victorian England and 1920s England are. So I'd say its location might be parallel to LWM. I work it out like this :
-Enchanted Forest = The Bavarian Forest and woods, as most of the Grimm fairytales reside there, such as Snow White, Rumplestiltskin, and Rapunzel, and the Brothers Grimm is German
-Maurice's town/kingdom, Prince Thomas' kingdom (where Cinderella is)= French areas, because Beauty and the Beast is written by French author Jeanne Marie and Cinderella by Charles Perrault, another French author.
-The Maritime Kingdom, Glowerhaven = Denmark. The Little Mermaid is written by Hans Christian Andersen, who is Danish, so I would say that Eric's kingdom is around the Danish Areas. Poseidon's boneyard might be in the sea between Arendelle and The Maritime Kingdom, and it might be the area where Ursula lures Hook's crew.
-Arendelle = Norway. It is obvious that Arendelle is Norwegian as Frozen is set on that country, and Arendelle itself is loosely named after a Norwegian city, Arendal. Arendelle and The Maritime Kingdom might make up the Scandinavian part of FTL
-Camelot = England. The Arthurian Legend originated from Medieval English so Camelot might be loosely based on the LWM version of Medieval England.
-DunBroch and the Scottish highlands = Scotland. DunBroch is said to be separated by the Ivory sea and not too far from Camelot. And DunBroch is located north of Camelot, much like in LWM Scotland is located north of England and is separated by sea.
-Agrabah = Arabic areas, probably there are other Arabic kingdoms near Agrabah so I can't say Saudi Arabia.
-Mulan's home/The Empire = Imperial China, Mulan's home might not be too far from Agrabah as both Arab and China are in Asia in LWM, and Agrabah is said to be separated by desert from EF so I'd say Mulan's home is near this desert, so the desert is between the Empire and Agrabah, much like how Eric's kingdom might be near the sea that separated EF and Arendelle, and the sea is between the Maritime Kingdom and Arendelle, this desert might be the FTL counterpart of the Mongolian Desert.
Idk where Aurora's kingdom is located, but by seeing the castle location and the guards' costumes, it might not be too far from Mulan's home, so it might be near the desert that separated EF and Agrabah, which could explain why Philip ended up near Mulan's home as the Yaoguai.