"Sand" is describing the noun "skøndhed" words describing nouns are adjectives not adverbs. You need to use "sand" because "skøndhed" is a -n word. Sandt is used to describe -t nouns and when used as an adverb
An example of sand used as an adverb is "Hun taler sandt" ( she speaks truly) here sandt describes a verb and therefore needs the t
As an expression, I would agree. But from a language learning perspective they may want to see 'sand' translated as 'true'
Real was accepted 2.07
I have a question for the German speakers... Can "sand" be translated to echt and, moreover, used instead of "virkelig?" when impressed about what has just been told?
Sand can be translated to echt
If you want to use it instead of "virkelig?" You would need to say "er det sandt?" You cannot just say "sand" that would just be sand (like sand on a beach)