The correct response should be "We love French dishes." No argument here.
However, it should also accept plates, as in context this would work fine.
What troubles me is that still today, if you say "We love the French dishes," it puts the words "love" and "the" together as if there is no space ("We lovethe French dishes.), and then tells you that you are the incorrect one with too many extra spaces.
IMHO, the word "the" should be accepted, as this is still a possibility, and also the "correct" response needs to separate these two words with a space.
The confusion here seems to be, what do they mean by the word 'dish?' Do we love the PLATES (and bowls and cups) from France, or do we love French FOOD (cuisine)? I would never, ever say "I like French dishes," unless I was talking about the actual porcelain items we serve food upon. Otherwise it would be French food or French cuisine that I like.
I think Duolingo is just introducing another word, like "gustar," that flips the sentence around, making "we" the direct object rather than the subject. Your question is perfectly reasonable given that quieren would use the more common sentence structure, but we need to learn both.