Interesting. Although I would speculate that Kinshasa and other African cities are not truly "French-speaking". Its an official and business language but probably not something that would be spoken in the home by a plurality of people.
Yes, when I made the quiz I was very sceptical about that! But it turns out Mandarin is used in the very urban sections so it accounts for more than half!
The dominating language in Kiev is Russian. I’ll accept Ukrainian for these quiz, because the majority identifies as Ukrainian despite speaking Russian (or a mix of Russian and Ukrainian), but Donetsk is clearly a Russian speaking (and identifying) city.
Also, are you considering Wu (spoken in Shanghai) to be the same as Mandarin?