On level 20 of this course - http://www.memrise.com/course/44611/basic-arabic-vocabulary-1/20/ - the English phrases “he is Afghani” and “she is Afghani” are incorrect. The actual term for the nationality is “Afghan”, with no i; with the i at the end, it’s the name of the Afghan currency. See https://en.wikipedia.org/wiki/Afghan
Because this course has used “afghani” for so long that many people are probably used to having to type the slightly incorrect answer, and because it does get used sometimes by English-speakers even though it’s considered incorrect, I would suggest the course keep the versions with i as alts and continue to allow people to give them as correct answers. But the main definition should be changed to remove the i.
P.S. I have no idea if the course maintainer is here, or will see this. Tried tagging @Ibrahim.Shakoor but that username isn’t on this forum. He was working through a lot of problem reports (including I think this one) on the old course forum, but then Memrise wiped that all out