Actually, the training says bishops and stake presidents should call the Help Line.
Others should immediately contact legal authorities.
I just called the Help Line to confirm the difference.
Bishops and stake presidents have to act according to responsibilities of "clergy privilege" (think client-attorney privilege) -- which can vary by state, etc. The lady I spoke with mentioned that "clergy" could actually be breaking the law by reporting abuse to legal authorities.
Those who aren't bishops and stake presidents have the responsibility to contact legal authorities immediately, and also then contact the bishop.