The problem, I think, is poor eye / hand coordination and is having great difficulty bringing her hands together.
I used to have this problem myself in a severe form. This is usually diagnosed as "poor eye / hand coordination", but I think that may be a misnomer in this case. It has nothing to do with the eyes. It is a lack of proprioceptive sensivity in general: as a person, you have no awareness at all of where certain parts of your body are in space and in relation to other body parts, so to speak.
I also suffer from this...Walking into doorframes and hitting myself all the time...I think even with good exercises it may be a slow process, so time should be given.
See if your piano technician can get you a silent keyboard. It doesn't have to cost much, and it is fantastic to solve that kind of problems, really! It is the aural feedback and the wish to "play with your eyes" that hamper improvement.
Do you feel that your kinesthetic sense changes periodically, or have you just seen steady improvement?
It's pretty steady. I have to indicate the conditions though:1) I have practised on this problem like crazy. I am now able to play ANY piece I have to do on my silent keyboard, no matter how complicated it is, but it was a path of blood, sweat and tears, as you can imagine;2) I use no medication whatsoever.3) I observe a strict regimen of balanced diet and enough sleep.
I think I'll try consistent silent practice, just like I've done with sight reading. Maybe not ALL my pieces (you have my respect!) but some of them. It would also be good practice on my weak memory skills, my aural memory is the one that I think is rather good and I rely far too much on it...
My performance coach has the opinion that this aural feedback loop is the cause of many problems in performance, even in healthy people.
You are lucky to have someone who understands your problem! No matter how much I appreciate my teacher, I just don't think she understands my struggles. Probably because I can sometimes (unintentionally) manage quite well...The difficulties start when I really try. She just doesn't seem to believe how much I struggle with basic movements even if I tell her. So I tend to find solutions on my own...very slowly and after a lot of frustration...