She exhibits the classic severe OTS symptoms: Reduced work tolerance, weight gain, sugar craving, poor sleep.
Her’s is a particularly severe case to last this long and indicates that either she has not undertaken an appropriate recovery or in the worst case that she may never recover.
There is only one avenue and that is with a very gradual re-introduction of aerobic base training. It is her aerobic system that was damaged by the excess of intensity and racing in her youth. This needs to be done very gradually: A 20min walk might even be too much to start with. And she needs to fix her diet to wean her self off the sugar.
I have had to deal with several over trained athletes and it is a very sad situation as you you and she are now painfully aware. What was once an entirely manageable training load now completely overwhelms her body’s ability to cope.