"The girl comes in and sits down on the sofa."
Translation:Bejön a lány és leül a kanapéra.
No, the the vowel-harmony rule is based on all the vowels in the word. There are some exceptions, but "Kanapé" is not an exception. It has both "deep vowels" ("A"s) and a "high vowel" ("É"), so it's a mixed word. Mixed words usually fine with both "-ra" and "-re", but sometimes one of them becomes the common form and we cling to this tradition. "Kanapéra" became the common form and we use it that way. (A great example who traditions defeat logical rules)