Humans who are not magicians and have little magoi are basically "goi". It is a derogatory term used by Matal Mogamett. Magnostadt's 5th district consists of the non-magicians, also known as "goi".
The kou empire is an empire/country. It's just that the organisation is sort of affliated with kou empire.(I won't explain much if not it may be spoilers) hence they are different
[Morgiana went to see her family "Fanalis" in Dark Continent but there was a Magician told her that he can send her there "Another Place" but she can't get back, On the other hand How The Fanalis Corps where helping Leam Empire during the war with Magunoshutatto?]--------------------
first of all, it's a MAGI who told morgiana that.
I think the leader or someone from fanalis corps (maybe Muu?) insisted on going to "that place" and he started to realise that he belonged there, and started reverting to his original form as a fanalis. Once he completes it, he probably can't change back (I forgot why though)
but the magi who talked to morgiana found him, and said that he was "too young" and sent him back, away from "that place"
Do read the manga for more details.