I think it’s awesome that you are using Sibelius to write music- that’s my notation software of choice too (though my main DAW is Garageband- hoping to upgrade soon)! Using actual musical notation is such an awesome way to analyze your own music and figure out from an objective standpoint why your music sounds good, or easily identify what is wrong if it sounds off. I am honestly not one to make comments on sound quality (hence my use of GarageBand). I think of myself as a composer first (albeit a hobbyist) and music producer maybe tangentially. :D I'm trying to learn though!
I’m happy to dive deeper into constructive feedback if you are interested though, in the name of growing and developing as a composer. I think the caveat is that anything I say is my opinion solely, and I am by no means an expert. One thing that I have found in my own music to make stuff sparkle a little more is automating the volume of individual instruments. I know that this is difficult in Sibelius as dynamic markings and crescendos etc get you part of the way, but don’t exactly give you full control. When I listen carefully to your piece though, I think there are a few voices that I think deserve to stand out in the mix a little more and some that can stand to be more in the background. At 21”, the low strings (I think cellos) have a really interesting part that rises instead of walking down like the rest of the instruments. I think that instrument in that moment deserves to crescendo throughout that rising line to be heard more clearly. Also toward the end, at 26”, the high violins come in for some harmony support, but by nature of what register they sit in, they come in quite loud and abruptly. This is an instance in which I would mark them down a dynamic, even if they are marked the same as every other instrument, to create a more "even" balance. I would also crescendo into that note to avoid it suddenly stealing attention from the melody. I sincerely do think you’ve got a good piece here and had to think hard for something to write about! I hope you find this comment helpful, if not, feel free to disregard!