I am grateful to you for sharing your problem with me, operating a computerized communications device for your daughter which is her means of speech.
I will answer briefly, without explaining the halachic background related to the disabilities handicapped, etc., and I hope I answer your questions. You can also pass this mail to others in need, and to relevant organizations.
Under the circumstances and need for utmost consideration I suggest the following:
A. The computer should be turned on from Shabbat eve and throughout Shabbat and of course plugged in to a charger.
B. If it is necessary to move the computer and disconnect it from the plug - if it is for an important reason you can unplug/plug the charger to the electricity using a Gramma method, i.e. have a Shabbes clock timer turn on and off every 15 minutes when the electricity is off you can then plug / unplug the charger.
C. The screen-saver should be shut off so that using the program won't cause unnecessary added actions.
D. Your child can definitely use this media, which has a capacitive touch screen, including playing the desired word audio through the internal speaker.
E. This applies also to kids who have reached Bar / Bat Mitzvah.
F. I do not remember exactly all the procedures, but if there is a click sound, when you press the screen it should be canceled for Shabbat (if possible in settings) and only use the playback sound of the desired word (or sentence).
G. If it is necessary for communication, and the parents need to use the device, they should avoid using the audio when clicking / touching.
H. If you encounter a situation where it is also necessary for parents to play the audio - 'don't worry'!
Rabbi Yisrael Rosen, an engineer
Head of the Zomet Institute