Welcome to heathcare Magic!
I think the disease of your sister is hardly treatable, she is likely to suffer a prolonged course.
The disease has affected the function of left brain which is the side of brain to control right side of body and our knowledge center reside here.
Aphasia-inability to speak rarely ever improves.
She would remain care dependent and this group of patient tend to have complications of bed ridden conditions like clot in leg vein, infections and sepsis
and ultimately go downhill.
Lets hope her suffering remains minimal.