Can this not also mean "This building with..."?
Of course, without further clarification, "ce" (or cette/cet) may be either "this" or "that". If you intend to be more specific, you may append « -ci » or « -là » to the noun.
But 'this' is not accepted
It was accepted for me. Do you know that if your solution gets a green flag, it has been accepted?
Would it not be more idiomatic to say, "Ce bâtiment au toit marron est une église?"