She knows nothing about bikes, so it wouldn't help.

She needs more torque because she moved from a flat to a hilly area. As an alternative to changing the primary gear ratio, we were wondering if installing a beefy rear hub might solve the problem.

Otherwise, the 39T+28T combo means she might spin too much on the flat, which is why I was wondering about the torque a three-speed S-A can take.

I did mean the Sturmey-Archer's CS-RK3 combined with a 7-9s cassette.