No one I know would say "Whose is the coat?" <Whose coat?> or <Whose coat is this?> Or even <Who owns this coat?> would suffice.
Please report it. I can anyway confirm that the Italian sentence is pretty fine. :)
It is correct English, just not used as often as 'Whose coat is this?'
Agree, 'whose is the coat' is not how it would be most often said in English