It's the opposite of delusional, actually: it's official government statistics. If they are claiming those numbers, it means the number of white people in Europe is even higher, since otherwise those governments would be bragging about even higher numbers of that "diversity" they love.
Not that this kind of guesswork is even necessary. Both left-wing and right-wing pollsters, agencies and governmental figures across NA and Europe agree with these statistics. There's a reason your post didn't include information counter to that post and why not a single person beside you even bothered responding to that post at all. Those numbers aren't up for debate.
There's criticism of european governments (who sure as fuck deserve it right now) and then there's cope. You're engaged in the latter. Take a break and come back with any one of the millions of ways one can criticize those countries' current ruling parties. It's not that hard.