"Does Mara understand, Torg?"
Translation:yaj'a' mara, torgh?
The order is indeed OVS. For this sentence: mara is the one doing the understanding (the subject), and as the thing that she understands is not specified, there is no object. Torg is the addressee which is not a subject or an object of the verb. The one addressed might be found either in front of the sentence, or after it, but the course requires that you put the addressee in the same place as the original sentence.