why isnt "Se on hyvä kysymys" right?
Tuo = that; se = it. (And tämä = this.)
I think Se on hyvä kysymys is some kind of a phrase, meaning "That ia a really nasty/complex question". I rarely say Tuo on hyvä kysymys, though I would literally mean it. It usually is "se". I think both answers should be accepted.
Se on hyvä kysymys should be accepted
Finnish works differently than English, so no, it really shouldn't.