"The staircase is made out of wood and is brown."
Translation:Die Treppe ist aus Holz und braun.
I suppose that could be counted correct if all you have is the English sentence. I suppose that whoever added the sentence was thinking of the original German sentence.
Note that Treppenhaus and Treppe mean rather different things.
Treppe (staircase, flight of stairs) is a collection of steps that you can use to go up or down.
Treppenhaus (stairwell) is a shaft or "vertical corridor" containing a staircase.
I suppose "staircase" can also be used, by extension, for a stairwell, but the main meaning of Treppenhaus is the space, which happens to contain stairs, rather than the stairs themselves. For example, you might say, Im Treppenhaus brennt noch Licht "The light is still on in the stairwell", referring to the "room" rather than to the steps.
Try doing an image search for "stairwell" and another one for "staircase". Most if not all of the "staircase" images show free-standing staircases, i.e. Treppen, while the images for "stairwell" show Treppenhäuser.