This reminds me of a rather daft television series in the UK, called "Meet the Ancestors".   It was presented by a professional archaeologist and the format in every case involved his turning up (invited) on an archaeological site somewhere in Britain or Ireland, where human remains were being uncovered.   Invariably, even if what remained of the skull were only a lower left molar and a lump of jawbone, face-reconstruction experts in London would be asked to create a reconstruction of the face of the deceased.   Producing a face became the object of the exercise, at the expense of providing much more interesting information about how people lived in bygone times.

When face-reconstruction was still a bit of a novelty, a couple of British universities collaborated with Greek archaeologists on finds from a site called Verghina, in northern Greece.   As reconstruction proceeded, all concerned became convinced that the skull on which they were working was that of Philip II, king of Macedon, best known as the father of Alexander the Great.  There were all sorts of big clues in that direction from the archaeological site;  the fact that the owner of the skull had survived losing an eye, as Philip is known to have done, made Philip a decent candidate.   The final result came out looking a fair bit like the head of Zeus on Macedonian tetradrachm coins from the fourth century BC, which had always been assumed to have been based on an idealised portrait of Philip, anyway;   when it came to the finishing touches, especially the beard, those reconstructing the face possibly used the tetradrachm head as a cue, which potentially amounted to something of a circular argument. 

I rather like the idea that we probably know approximately what Philip looked like, thanks to the reconstruction from the Verghina skull.   I don't think that there is any reason to doubt the accuracy of the reconstruction, before the addition of facial hair.  In contrast, many of the ancient "portraits" that we have are assigned on a very flimsy basis and even those that can be confidently identified may date from well after the death of the individual portrayed (for that matter, Philip's coins were minted for decades after he was gone, as were Alexander's).    Ultimately, though, having a likeness of a figure from history doesn't tell us a huge amount about him or her.   Skeletons lack the essential spark of life.

Portraits may capture that spark, or they may not.    We can't tell, once the subject is lost to us.   In the case of Bach, we are asking whether one artist, in oils, has captured the essence of another, one of the greatest of musicians.   It's safe to say that no scientific reconstruction of Bach's head is going to shed any light on his genius.   On the other hand, if we lacked any inkling as to his appearance, his genius would remain undiminished.