"No, you do not go."
Translation:No, voi non andate.
how can we know if "you" refers to more than one person? we have to peek, right?
You don't have to, since there is no context you can translate this as "No, tu non vai" or "No, voi non andate". Even "No, Lei non va" (Lei = formal you ) should be correct.
I would disagree. It absolutely matters if you're talking a specific person, or to a group. What DL accepts is irrelevant in regards to the question.
Sure, if you have context. Without context any of those options could be correct, so any should be accepted.