This could all be fixed if it’s revealed she had a bit of training as a toddler by some forgotten survivor of the Jedi purge. 😉
I’d find that neither satisfying or necessary.
I watched TFA again the other day on TBS and I disagree even more now. Unless knowledge of how to use the force transferred to her from her mind link with Kylo, the simple fact that she on her own thought to use the Jedi mind trick needs some sort of explanation…unless I am forgetting something. Like, you don’t just come up with a Jedi force skill out of thin air at exactly the moment you need it. She doesn’t have to be a Skywalker, she doesn’t have to have a lineage of importance, but she has to have had some training early in life.