Martin, I don't think anyone has or not that's been confirmed on any forum. I understand it would indeed be an enormous task but one that a lot of people would be interested in. The impression I have had is that the Sibelius folk are just too busy. Perhaps it would need a coordinated effort where perhaps several people took on a chunk each. But as I don't now how to create a sound set I don't know how difficult or time consuming it would be. If A central person was to produce an idiots guide and it was not too onerrous I would be willing to join in (doing Brass as I have all three sets).
Would you be willing to step up to the plate?
Would anyone else be willing to organise or join in such an enterprise?