Peace,
My only concern is you've used Al kitab to translate as the record and the scripture. Why translate al zbr as both when Al quran has the specific words for those i.e. al kitab? Furthermore, How do you determine where to translate it as the psalms and where to translate it as the scripture,or the record? Although, David is one of the recepients of Al zabour, it is not exclusive to him (3/184).
I understand what you are saying, though the Arabic language does allow the use of different words sometimes to give the same meaning (e.g. Layth = Lion, Qaswara = Lion, Haitham = Lion, Asad = Lion). I did recheck the dictionary defintion on Zubr and scripture/book is one of its given meanings.
However, you are correct, the Quran is a precise and accurate work of art which uses different words to allude to slight variations perhaps in meaning. Is there a better word to use than scripture for zubr? I don`t have one, but if you do, please propose what options can be chosen from.