I think you misunderstand what Hiero is. From what I understand, Hiero is really more a system for connecting Nuke artists together and easing the flow between Nuke compositors with a finishing system like Smoke or Flame.
This text is taken directly from the Hiero product page:
HIERO is not a compositor, system for finishing, grading or editing, it is a pipeline scriptable shot management tool. A timeline for NUKE, but not exclusively, HIERO also enables collaborative working with other editorial, VFX and finishing tools.