Hi! I've listened to your track a few times, and I think the biggest area for improvement is the way the instruments interact dynamically.
What I mean is this: try dropping the solo part out for four bars at some point. Or do the same with the piano. When it comes back in, it'll have much more impact and create a stronger sense of movement for the listener. Right now, the texture stays at almost the same intensity throughout, which makes it feel a bit monotonous over time.
The lower violins also sound a little muddy to my ears. You could try shaping them with a series of crescendos followed by softer entries, almost like waves. That would give the arrangement more space to breathe.
As for the mix, I can only comment as a listener. I think the midrange could be brought forward a little, since it feels slightly recessed. Also, that reverberant "thump" every two bars is a really interesting element, but it doesn't stand out enough. I'd try bringing it forward a bit more, either by raising its level slightly or giving it a little more stereo width.