This is a bit strange.
You have a fourth year student who appears to do most things wrong.
But can she play? Or does she just look funny? You probably can't change everything, and it may depend on her goals.
Also, have you taught older students before? Some of us do a lot of things funny. <grin>
Just a quick story. At Oregon State (I think that was the location), which is a hotbed of elite runners, they did a study on amateurs. They took a group of amateur fun run clutzes, people who look funny when they run. Their elbows stick out, they wobble, they bounce, etc. All you have to do is take one look at one of their scholarship track stars, and you're stunned at the difference.
Anyway, they took the group and coached them intensely on form. Posture, arm motion, balance, breathing, the works. After a month or so they were able to convert all of them to a decent level of running form. They all looked good.
Performance? Well, measured by times, distances, VO2 max, etc., - none of them improved a bit. They all looked better but didn't really run any better.
I'm not saying this applies directly to your student. She may really have deficient technique that will limit her progress. But I think with a student that old you have to evaluate what is really limiting bad technique, and what is just idiosyncratic, because you probably can't "fix" it all. I went to a golf pro once, and he said I had naturally developed an SA swing, and at the pro level that would limit me, but at my level I would be far better off maximizing my current pattern than trying to convert to CG.