1. Not much to critique here... It is simple, it is adorable.
2. That being said... I suppose one minor detailing to mention is Apple Syrup's freckles. Since you are using a lighter shade of orange for Apple Syrup's fur-coat, white freckles can be harder to define artistically. A refinement suggestion(s) can be that you may want to sharpen her freckles by adding ultra-thin black outlines on the freckles, or enlargen her freckles to be more noticeable.
3. As a creative suggestion, if you find yourself doing another like this, you could have a scene where Apple Syrup's head is all but covered over by Applejack's stetson, with only a goofy grin from the little filly showing from underneath. Meanwhile, both Element parents look upon their daughter with joyful amusement.