I think the artificial part people are hearing consists of two things in the violin, and it may or may not be correctable, since I dont have any of Vienna's libraries outside of the special edition complete.
1. Its the vibrato on the violin. It is exactly the same for every note that is making this sound artificial. Also, the vibrato starts at the beginning of every single note... Vibrato should be expressive, and some notes should have it, some should not, and some notes should have vibrato added to the end of the note. In rare cases, vibrato at the beginning of the note and then moving into a straight tone even works. As I said at the beginning, I dont know if this is correctable with the library you have, I know with the special edition library, it is not, I have no way to control when there is vibrato and how much vibrato there will be (sadly).
2. Every note in each section of the piece has the same dynamic, each note has a soft crescendo and de-crescendo. This part you can fix, try having some notes without having the crescendo or decrescendo.
A bonus tip, EQ the violin if you can, bring the highs down a small bit and boost the mids a smidge, in particular, the lower mids. It will give the violin better tonal character.
It is a fantastic piece, and I dont mean to dump on it, absolutely wonderful. I particularly like the middle section, it has a bouncy, yet almost slightly somber tone to it. I almost wonder how this might sound bringing the ambient mic's up a bit on the piano and bringing down the closer mics a tad. The distant nature of the piano might add a sense of loneliness to it, as if the piano and violin were two friends that found each other. Thats kind of the impression I got...the beginning is two lonely instruments, like two lonely friends, and then the mid section, they find each other and they are so happy to have found each other..