No experience with that, but I may suggest the following:

– Rotate the angle of the bars (free). Sometimes, a few degrees make all the difference.

– Raise the bars, using either a steeper stem or by moving spacers around. At the same time, use a shorter stem so she would be less stretched out.

– Is it her left wrist by any chance? We often shift with the right hand, take water with our right hand... so the left moves much less. She could make conscious efforts to move her hand and do a few wrist rotations once in a while.

As for the brace, she should make sure it doesn't create pressure points in her hands or that it cuts blood circulation.