The inappropriate movements you are experiencing do indeed sound like synkinesis and while I have had excellent results with NMR you are only 4 months in and the flutterings and tuggings you are feeling can be associated with recovery as well as synkinesis and hypertonicity.
I think you need to feel confident in your therapist and you wonder whether you are getting all the information as she is running a business and essentially are questioning her motivation at therapy which is a viable concern. However she does sound like she is experienced and her policy against using ESTIM is a good sign that she knows what she is doing.
My opinion and it is just that is, that at 4 months there is still a lot of healing for you to do. If you feel that you need to take more time to see how your face will recover without the therapy then you should take it. Your therapy is meant to heal and relax you and if it is causing you concern then it will not accomplish that.
I don't think it is pompous to have information and to ask questions and your therapist should have the answers for you, it's up to you to take that information and make an informed decision that is right for you based on your own research and your comfort with your therapists recommendations.
I can't imagine accomplishing the level of recovery I have without the help of my therapist but I was much further along and my synkinesis was well established before I started the NMR and had the regime catered to my specific needs.
Wanting to push ahead and find something to do to speed your recovey is perfectly natural and I think every single one of us has wanted that quick fix but it may just be that you need to give yourself a little more time to feel like you are at a point where the therapy can help. If you feel that you haven't completely healed on your own then taking more time until you feel comfortable with the therapy may be what you need to do.
Talk to your therapist about it and let us know what she says.
Come back and let us know how you're doing.