1. Solid quality work here as with Pinkie Pie. It was the correct artistic call to have the prosthetic leg resemble more a "hoof" than a foot, it gives the audience subtle visual synthesis between your humanization and the pony source materiel.
2. Though... No Stetson? Was it lost/destroyed? Was it passed on to an older Apple Bloom? Or to her (your) OC-daughter Apple Syrup?
2. I am a bit surprised that you did not scar Applejack more, though. Generally, Applejack is the one on the receiving end of physical punishment (in slapstick comedy fashion, of course) among the Elements of Harmony.
4. I figured as much about Applejack's Stetson going to Apple Bloom, assuming you did not destroy it. That and OC Apple Syrup wears Apple Bloom's ribbon.
5. As for more scarring, that the tragic nature of bold characters like Applejack and Rainbow Dash (or Real Life heroes, such as fire-fighters, soldiers, & field medics), to have more injuries than others. That is the price of being someone who often stands at the forefront in the field. So it actually would have been reasonable to have a Dark Future (DF) Applejack almost as heavily scarred as DF Pinkie Pie. But that is a minor passable detail.
6. I would think you would have your OC children in this Dark Future. Gives you a chance to show them grown up to their respective parents' ages when the "Mane Six" first stood defiant against Nightmare Moon. And how the OC children may be the salvation of this Dark Future (possibly as the next bearers of The Elements of Harmony, or something).