Where are your family cannot be a correct translation because it isn't grammatically corret in English. Family is a singular unit, although a family has many people. Where is your family is appropriate. Where are you parents and siblings is also correct. But family as one unit would be where is your family
Sorry, you are incorrect for non-US English, where a family is always referred to as a multiple. Duolingo is strongly US based, but they make allowances for non-US usage, such as using the word 'biscuits' instead of 'cookies' and 'sweets' instead of 'candy'. In this case, with only the US treating the word as a single entity, the use of 'are' should be allowed.