I typed in "You are sweet" and it automatically assumed вы.
Actually, now that you mention it, the online translator ALWAYS uses вы.
May be it's a nineteenth century translator.

It was customary then to use "вы" in almost any case.
Even between close friends or husband and wife or mother and children.

"ты" was left for the lowest class people.

You're so sweet. = Вы так милы.