This seems out of place.
From the Tips & Notes of Verbs: -ig/-iĝ
ESPERANTO AS AN ADJECTIVE
It so happens that the word Esperanto is often used as an adjective, without an -a ending. (For example, there are more Esperanto clubs that call themselves Esperanto klubo than Esperanta klubo.)
I don't really see the point of this being taught at all, especially not in this lesson. I was reading through the Tips & Notes section and thinking that this was all very good, until I came to the last part of it, and for the life of me I could not understand why you would teach incorrect form in a language course.
Calling clubs Esperanto klubo without a hyphen is considered bad style as it breaks with the rules. We have the same problem going on in Norwegian with two nouns being placed after each other (like in English, instead of adjective + noun or noun-noun) and this is frowned upon as it only causes confusion. And at the very least it is not taught in a course teaching the language.
May I have some insight as to what the meaning of this part of the Tips & Notes was? And is there a real point for it to be there?