Yes, stairs can get quite complicated as shown by the last image I posted.
With open sided stairs the tread will typically overhang the stringer so that the nosing wraps around.
Both sides can be open sided full or partial so it does get a bit complicated.
I have no idea on mitering risers and stringers but I will need to look at that at some point.
A special first tread is also common as is the first baluster or post. Then there is the hand rail and possibly the balusters which forms a balustrade.
I’m really not wanting to dive into this too deep but at the same time I would like it have it flexible enough for most designers to represent a simple staircase in their design.
I could go so far as to dive into housed stringers but that is really above and beyond the scope of the plugin or at least what I am willing to consider right now.
Then there are landings, curved staircases, spirals, free standing, single stringer systems, steel and concrete stairs, etc…
However, I am very curious right now on how exactly one would frame up the stair stringers for the partially open staircase shown in the photo above, assuming that side spacers are employed and skirt boards.