Sentence:  That this incomplete work was presented <WSD>unstaged</WSD>, without orchestra, and with little attention to dynamics, and that it was sung by singers difficult to understand, generally in poor French (with no libretto or plot synopsis in the program--either in French or English), prevented this from being the revelatory experience it might have been under better circumstances. 
Meaning of the word marked with <WSD> tags:  Not formally staged; not presented to an audience on a stage.