But in this case, it is only said that "the adverbial may follow the
object noun", but nobody talks about question words. So we could start a
discussion if a question word is an adverbial?

I think this only aplies to adverbials, but I think that is sounds quite
right to use questions in there as well.

I have no problem at all with allowing qatlh and chay', which work just like adverbials, to substitute in the adverbial role for "fronting" objects.

Imagine you've just murdered a guard. Your friend sees the body, looks up at you wide-eyed, and whispers: 'avwI''e' qatlh Dachotpu'? The guard! Why did you murder him?

-- 
SuStel
http://trimboli.name