The idea is quite good but there are still some mistakes. I found these: Light blue in it (San Marino also has), Bird in it (Serbia), white stripe at the bottom (Serbia), doesn't have white (North Macedonia) ... please check this.
Sorry for the late reply, I just didn't want to answer till I correct the quiz. Thanks for letting me know these mistakes, hopefully the quiz is now correct logically.
Unexpectedly challenging! :) At first I thought it was going to be a piece of cake with the huge amount of time given, but in the end I only got a little over a half done before the time was up.
Otherwise: Great quiz!