what about 'he does not look normal'? Seems more natural.
True, but grammatically it's a completely different sentence. We have to keep more or less close to the original.
And how to say it in a natural way in Polish? "On nie wygląda normalnie"?
Or "On wygląda dziwnie/dziwnie wygląda", using the word for "strange".
Why not: His looks are not normal.
Our native speaker experts decided that it does not work well in this sentence.