Rafiki is not in the first noun class. Rafiki (class 9) can be both singular and plural; marafiki (class 6) is plural (friends). Although in class 9, adjective agreements for rafiki follow class 1/2 (animate beings). So a good friend is 'rafiki mzuri' rather than 'rafiki nzuri'. But possessive agreements are based on class 9. So 'my good friend' is 'rafiki yangu mzuri' and 'my good friends' is 'rafiki zangu wazuri'. I'm not sure how 'marafiki' would be used like this, it would either be 'marafiki yangu wazuri' (class 6 possessive agreement) or 'marafiki zangu wazuri' (class 10 possessive agreement). I'm not even sure if they'd still maintain the same adjective agreements of wa-.... anyways, best to stick with rafiki for singular and plural
"Rafiki" can be singular and plural for "friend." "Marafiki" is only for plural (friends), but "rafiki" can be both singular and plural.
My question was why the plural for "rafiki" is "marafiki" instead of "warafiki."
Ahh, okay. Sorry, I misunderstood the question. Rafiki/marafiki is correct but I wasn't given a proper explanation, just told it's an exception. Maybe someone else can clear that up
"require" makes it sound like it's written in an official rule book somewhere.
Same meaning, but a bit strange of a way to say it. If you report it, they'll probably add it eventually.