Nice quiz, I really enjoyed it! Somehow having the continents and the first letters for each country makes it a little too easy for me, would be fun having a version without those hints and just the map. But really great!
It's pretty obvious this quiz is taken in English, so any other name written in a different language isn't accepted. Now I know that for Ivory Coast and East Timor the diplomatically recognized name is the one in their own languages, the first one for national identity and uniformity reasons (childish in my opinion but who am I to judge), and the other one for a technicality after their translation (East Timor, fully translated from Malay would mean East East), but considering this is a specifically English language vocabulary test, I cannot include their names in French and Portuguese, because it would defeat the purpose of it. This quiz doesn't take into account diplomacy and the United Nations terms for recognizing a country, it only takes into account the vocabulary and the English language, so I would have to accept also all the other countries names in their language, and the quiz would be completely different. I hope I answered thoroughly.
Also addressing to the Czech Republic matter, as the other guy said before me, when you type in the word Czechia, you're typing in an automatic JetPunk type-in, that helps users get the answer quickly, but it doesn't represent the countries official name, almost the same (but slightly different, considering they're acronyms) as ROK, DPRK, USA, UAE and many more.
there's also a version for every vowel, with and without the map. Check them out? 😊