Peace be with you, guys!
The more I read, the more I get the impression that you are talking about different things.
Mats, I think it is not entirely clear in what way you want to be different (and in what way you don't).
A "traditional" interpretation of the piece would be faithfully sticking to each written note. By that, one wants to re-create what Grieg initially intended, even if every recording will sound different.
As you changed notes and articulations and even added parts that were not composed by Grieg, you may want to create some kind of re-invention or re-arrangement of Grieg's Work. Therefore you mentioned people like Vanessa Mae who also don't take Grieg's sheet music literally. Today there is no reason to criticize this approach.
But does it forcibly have to be boring to play a musical work in the way the composer has intended?
This reminds me of the different approaches when e.g. producing/staging an opera. Does the scene have to look like at Mozart's time, or do we have to translate it into the world of today? You won't find an answer that is valid for everyone.
What I still didn't completely understand is: Do you want your version to sound like it could have been played by real human musicians, or is this realism not part of what you wanted to achieve?
One could also use synthetic sounds or create a "collage" with snippets of recordings...
But the moment you choose an orchestral library to emulate the string ensemble intended by Grieg, you will automatically be compared to live recordings of "human" orchestras. And I agree with those who said they'd easily hear that your version was created by programming.
There are many types of listeners in this world. To judge if a production sounds realistic, everyone will rely on different criteria, different details of what we hear. Everyone has his own perception, nobody hears the entire reality.
(Does a child resemble his mother or his father? Ask ten people and you'll get ten completely different opinions.)
Even musicians with trained ears will hear real instruments, because this is what libraries are made of. But someone who is used to work with these libraries will hear with different ears than someone else. As you pointed out yourself: It depends on the listener's experience.
Regards,
Klaus