Honestly, I think the whole thing about dark magic isn't correct. If you think about it, this world she was put into had these things set in stone. The confrontation was an "event" set to trigger after something had happened. So my theory is the world itself tried to make these events take their proper course, but those who had been in close contact with her had changed enough for this to not affect them. That would explain the memory gap, as well as why those documents existed. They made them using "events" that were SUPPOSE to happen, but never did.