I also don't like that fixtures at top and bottom are SPOF. Why not add pillars to the top and ~3rd from bottom steps, then tie with another beam, like an H overlapping a ladder?
That way, there will be far less chances that bolts spontaneously rip off and stairs go down, nor the lengths of pillars to have to be critical dimensions. The pillars can optionally be cut to precise lengths to be screwed through both steps and slopes for maximum Apple-ness, or, can be lazily cut to long-enough lengths, nailed through to steps from the "outside", and used as base for handrails as if it had been the plan.
(dc: not an engineering advise. consult a real engineer for safety. Also add cross beams in width-height plane, they help tremendously)
That way, there will be far less chances that bolts spontaneously rip off and stairs go down, nor the lengths of pillars to have to be critical dimensions. The pillars can optionally be cut to precise lengths to be screwed through both steps and slopes for maximum Apple-ness, or, can be lazily cut to long-enough lengths, nailed through to steps from the "outside", and used as base for handrails as if it had been the plan.
(dc: not an engineering advise. consult a real engineer for safety. Also add cross beams in width-height plane, they help tremendously)