You might want to look at page 237 of the Backstage Handbook III.
There is a crucial table presented on it that explains what's going on with your very broad figure.
Remember that 17" or 18" golden rule, or the 2R=T=25 rule of thumb formula are goals for normal building purposes. With those golden rules, there are minimum standards set by the UBC about minimum and maximum tread and riser dimensions as well as info about ladders and ramps.
For stage use, you can do what you need to since it's temporary, and those using it will have been trained in it's potential danger. Just like acting on a raked stage. The more the slope, the more the danger. The more you avert from a 11" tread and a 7" rise, the more dangerous that is going to be for the person using the stair. About as dangerous as installing a half height or 1.1/2 height stair at the bottom or top with out a landing. It's best to use that golden rule and slightly modify your treads and risers to fit in your space.
That's given you are not contiously making use of averting from the 18" standard say to help the talent find their role in the set being off kilter visually and by engineering of it. Kind of like both raking and sloping your set ever so slightly. Or cutting 1/4" off the leg of a 3-legged stool. Such design things are not enough to be heavily noticed but they can be felt.
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