Only started looking at the flags yesterday, I dont think I would ve been able to accurately identify more than 8... If I got some leeway and got 3 attempts per flag maybe i would reach 15.
(let me think... canada, usa, uk, ireland &italy (but probaly guess right), netherlands, france, luxembourg, belgium& germany, (probably guess right). Sweden. OW and greece, argentina and israel . Ow and mix up spain an portugal.
The other scandinavian countries in one lump. the swiss one if I didnt say austria. and probably china, though I might say russia first. still had the soviet flag in my head...)
Hmm it looks like I would ve know atleast 15 instead of 8. Anyway, as you can see, not a flagperson at all haha.