Ok, so here is your mix.
With your CV and previous comments (and regarding the title as well), I expected some classical additions but I don’t have idea of which ones.
The result is quite odd for me since I have another idea of that song.
Adding violin or cello is a nice idea and I thought it was what you ought to but the meaning of the song, of the playing and the story doesn’t call for that addition from my point of view.
I mean, it’s kinda rock/ballad song with every rock parts (except bass guitar) and I don’t see violin in that song.
Plus the song is based on that arpeggio clean guitar that play in duo with the lead vocal: you could remove every other tracks, the song is still working.
That clean guitar has a very simple pattern during the song and the song itself is very straightforward. No fancy part, no incredible instrument or playing.
The violin part you added sounds more as a soloist trying to playing along the track, which is more or less what you did. The lack of simple pattern (like the main guitar) work against the song to me.
I think on that part, you would take your producer hat and tell the soloist to play more in the spirit of the song.
What also needed in that work is making some room for those additions (some cuts or so) because it sounds to me on top of the song and not into the song.
Mixing-wise, I agree with some previous replies saying that strings part are a bit too bright and it sounds a bit disconnected to me.
The same for the reverb choice: there are some printed on the raw tracks and at times, it doesn’t really match…
By the way and despite what I wrote, you made a pretty strong work, very bold specially regarding every other mixes and the original song.
Very nice job and many thanks for sharing all your advices, knowledges and passion for the music!