I wrote ' The Canadian man is in a red shirt", which was not accepted. But actually this translation is closest to the Hungarian and it is a construction that is also used in (at least) American English " She is in a black ball gown".
That sounds awkward and strange to me. I don't hear people describing someone wearing something in that way. However, "The Canadian man is in a red shirt" is valid (but see the post above, it was rejected 3 months ago).