Great quiz! Love having the map for this. My best score on the no-map version is 71, but I got 80 on this version because I could see which ones I was missing.
For Grande Comore You should accept Ngazidja (Traditional, correct way to spell it and how it appears on a good bit of maps, and Grand Comoro (Anglicized). Sat there and guessed both like 4 times and still got it wrong. Even googled both to make sure I wasn’t crazy they’re both correct ways to spell it alongside Grande Comore. Almost like accepting Côte d’Ivoire but not Ivory Coast if this were countries.
It's really close between Iceland and Grand Comore for the 100th spot, but I took the answers for the quiz from this other quiz, which doesn't have Iceland on it.
You can take it up with Wikipedia, because the data is taken from there (I try my best to be consistent with the original "Most Populous Islands" quiz).