Traction control may have assisted this event, but enough to avoid it?
"a friend of mine crashed when she had to swerve onto some wet railroad tracks to avoid a car. As she described it the engine revved, the rear wheel spun, and she went sideways and high sided." By that description I'd assume this was multi lane traffic over a set of tracks that angled across the road.
I am a strong advocate that the rider must assess ALL aspects of the riding environment to avoid reactionary measures. Sure, its really easy for me to asses this at my desk. But factors like wet road/railroad tracks/traffic interaction sounds like many clues to be ready and to avoid close proximity to a car before entering the area. All relates to effective scanning/searching before getting there.
Tracion control is a good assist system, but the best "system" is and always will be between the rider's ears. Traction control starts in the brain and works at the eyes, hands and feet of the rider. Hope she's up and riding again!