Suggested progression; Try a softer and larger diameter grip area. She has her shoulder weight bearing down on her hands. Having a downward tilted seat is a hand killer, make sure it's flat. Lastly, you may need to make her position more upright. In the most extreme cases you may need to use a drop/road handlebar and flip them up and use foam padding. I use to live/ build tandems in Encinitas. Do you ever take your tandem up to Camp Pendelton (our old favorite)?