I like this track. It has emotion and feeling. I wouldn’t think of it as a trailer track though, but more of a credits track or cinematic underscore. A trailer track is usually more bombastic.
Regarding the mix I don’t think it’s very bad at all, but as Adam said, it could be a bit muddy so some cleaning up in the lower register could help, as well as adding a tad bit of shine.
I think this should’ve been a soft reject at worst, and it could also be a mistake as we’ve seen happen before. The reviewer may have felt that the string melody is a bit unusual and therefore not commercial enough. It goes to places the average listener might not expect. Something I don’t think is a bad thing, but what can you do…