A good air squat needs good ankle mobility, significant amount of linear stability (thoracolumbar+inner units+ hips - activation of the glutes and hams.), re-teaching of a movement and correction.
Problem is balance after breaking parallel where the torso dips forward due to the fact that the left ankle doesn't allow full flexion and is limiting ROM, hence the center of gravity is tipped forward as the weight goes to towards the toes.
Trying to correct that from day one with lunges/ankle mobility drills/activation of the glutes and hams/mini band box pistols/air squat and box squat drills.
Rather than wait for her to gain back full mobility which i doubt will happen so soon, a SS will give the benefit of squatting.
However the rehab/strengthening program has gotten her from being a knocked kneed squatter/quad dominant in the beginning to a lil past parallel which is by hindsight is an improvement in her movement but then again i know nothing, so doesn't add up to anything nor can it be called a feat.
Rehabbing her from severed nerves and inner unit musculature in her mid section due to a cesarean birth, to doing an ab wheel and now a full turkish getup with 10kgs which i think for you is child's play.
oh not to forget the little detail of working around a subluxation of her C5.
I think its a miracle, that i'm able to do it. I think its more a Fluke...
If you have better methods and can fix her within one session, i'll gladly bring her to you and pay you the session fee.