1. The pacing is a bit quick I think. I think it would be better if you slowed it down.
2. I think exploring all of Equestria, to find the princess is a bit too much area to cover even in months. I think you need to reduce the scale of it. Maybe make it just the area around Bee Chamgeling area.
3. I think it was foolish of the king to admit his daughter is missing to the general public. A report like that could cause untold worry to the changelings. I think he should've tried to hide the fact especially considering that a possible kidnapping could very well have been caused by creatures with rival political interests who could use the uncertainty to their own benefit.
4. I think Arctic's reasons for accusing Everbrook are too unreasonable. That being she was the only one available. I think it would have been better if Arctic had at least somewhat legitimate clues and reasons that she did kidnap his daughter.