There is also a music language which is learned by a musician and is understandable to a listener. Music is played by rules sometimes quite plain sometimes subconscious for a musician, but absolutely unknown to a computer. And when we talk about expressive performance concerning computers it is too early to speak about gift and insight. First of all we must teach computers the basics of music language and rules of sound producing which it so easily breaks. It is impossible to write computer programs based on impressions, emotions and words - an engineer needs logical expressions of performance, concrete algorithms, rules and digits.
Computers have to be taught performance modeling.
Notes and playing them are different things. Conceptually, a score is only a plan of performance. So a computer as well as a musician should study playing a score with a lot of nuances - volume changes, tuning, tempo and so on but not simply playing back music. These changes can be imagined as many parameter functions which transform source data - the electronic score. Obviously, we need a performance modeling program which is able to observe the rules of musical language as well as a live performer.