A nice, pleasing ballad ! I like your orchestration and your mixing was okay.
I think it's a little bit harder to immerse with this track since it's more upbeat and light than what the painting seems to represent, though that might be partially biased from my taste. The reverb and instrument choices are still faithful to the cold feeling.
I like the fact that you introduced a rhythmic change in one of the sections, but I think it would benefit from a harmonic change too. Usually when there's a change in pace, it's met with a break in the harmony, you take advantage of the faster pace to have a more resolved progression. This may sound very specific because that's what I'm picturing, but tldr : don't hesitate to introduce harmonic change too, since the chord progression pretty much stays the same throughout the track. The tonal monotony can clash with the rhythmic diversity you created.
One last advice I'd make is to pan the orchestra's instruments relative to how they're placed in an orchestra. Widening the stereo range of the piano was good, but I'd have liked to hear the flute slightly leftwards.
Otherwise, that sounded pretty good, especially for someone who's not used to ambient work. Keep up the good work !