Do you have other joinery gong on, or are those legs relying on pocket screws to hold the load? Is it going to stand up to the racking forces that chairs take?
Did you start from the cushion size as your base dimensions? I’m thinking about doing something similar and trying to decide on how to figure out the sizing.
I would personally give them a little less depth in the frame where you sit. Less likely to have the legs from the front of the seat of the chair when the cushion compresses. And maybe I'm just shorter than everyone else.