Why can't this be translated more literally as "He is standing very calmly on stage"? Surely that's a valid sentence?
Yes, you are right, it can be. Both have the same meaning and it's valid.
Even yours will suit better by the tense of sentence, if a literally translation will be made.
"duruyor" is not used as "standing" here, used as "looks".
Why not 'he appears very calm on stage'?
Yep, that's what I put Bjorn - which is of course, exactly what one would say in English :-)
I put a HE on stage. Why do you insist in SHE? As I know, the turkish language has no genders.
I answered so still instead of very calmly. Why is it wrong?
Does "sakin" respect the vowel harmony?
Not within the word itself, but it isn't a native Turkish word. It is from Arabic.
I do not have the audio !i have reported for more than a hundred times and still there comes a single answer ." Thank you for your feedback " . Is it really what i need ? I am so sorry !