The planet is known by many other names, including Vomestra, Od-Di-Pa V, Tum Lux O-Ty, and Alata Zerka; all of these meaning "Green Planet" in some language. In the book E.T.: The Book of the Green Planet, a "former world" that E.T.'s species used to inhabit is mentioned, so it's possible that they are actually not indigenous to Brodo Asogi. Since "Brodo Asogi" means "Green Planet" and they address themselves as "Children of the Green Planet", this appears to be a contradiction. However, they may simply refer to whatever planet they're from as the "Green Planet", which would explain the inconsistency.