When looking at the Codex entry in the end of chapter three on the Human Coalition and XCOM, it is surprisingly short when compared to the entry that the Systems Alliance have in canon. This is most likely because of the Coalition's mistrust of aliens and institutional paranoia, therefore they deliberately reveal as little about the inner workings of humanity's society and government as possible to the outside. And with far fewer humans living outside of Coalition space, very few aliens have any additional knowledge on humans beyond these basic facts...a mysteriousness which is itself admitted as being a major cause for the fear that the rest of the galaxy feels for humanity as a whole.
, it is surprisingly short when compared to the entry that the Systems Alliance have in canon