To anyone who wants to leave their comment, I am sorry Kiev is not accepted. It was a political decision of the administrators of this course. I'm personally against it, but can't do anything about it. I agree with most of the comments about history, pronunciation, foreign languages and standards and so on. But please stop spamming in the comments. Repeating the same arguments again and again in each sentence discussion creates clutter....
I am totally voting for accepting Kiev too.
It's the most common official spelling in English. People spell it that way not because they don't think Ukraine is an independent country, or that Ukrainian is a language different from Russian, but because it's just the spelling. We also spell "Rome" and not "Roma". Yes, this spelling comes from the Russian word "Киев". But. It used to be spelled as "Кыѥвъ", so there is indeed connection with "Kiev" which is deeper than just the Russian language. Also, since nobody knows how to pronounce "y" and since short "i" in English sounds quite similar to "и", spelling it as "Kiev" makes sense. Yes, there is #KyivNotKiev. And yes, several countries have already made it their official spelling. And some media are using it in support of the campaign. However, that does NOT yet make "Kiev" wrong. Especially if we're talking language and NOT politics.
The other mods and the admin do not share my opinion. Or rather, the admin told me that they had a vote and decided to abolish "Kiev". I haven't heard from other mods.
The "reasons" listed in the Incubator are just links to media following the #KyivNotKiev movement, and links to Duolingo forum discussions about it, not really the actual final reasons that decided the outcome.
I'm sorry that it's like this :/