Yes, It's trail and error. I have severe back problems and can only ride a LWB recumbent. Riding an upright much leaves me with enough pain that I don't walk for a day or two. In fact, riding the bent is about the only time I am pain free. But I do have one friend who was the opposite. When he rode a recumbent he got sciatic nerve pain down his leg.
But by and large, I talk to far more bent drivers who have no back, neck or wrist problems with a bent than otherwise. But have her try the above suggestions and hopefully find something that works.