Only for very little kids you would use that in the netherlands (and not used by everyone but it's not incorrect/dialect eventhough it might be regional). It's never used for an adult. (Because the adorable+ obedient just doesn't work after a certain age)
It's would be used as a synonym for braaf. So welbehaved and quietly enjoying themselves.
(Lief would be the translation for sweet)
It should. If it happens again check for errors and report ( In case you missed a word (it happens I've done it..) Or typed sweat instead of sweet)
Sometimes some correct answers aren't in the database yet. (Though you'd think the two tenses are the first thing you think of to put in. Sometimes there are a lot of different ways to say something so it's easy to miss one (or more), but the tenses should be a reflex, add one at its counterpart. And most definitely the counterpart of the standard correct answer shown at the top of the thread)