>>24607621 (OP)
Not a terrible question.
I and others made the mistake of thinking that geometry for instance was essentially constitutive of the world-as-experienced for Kant. But it turns out it isn't - we don't behold circular objects on the basis of a preexisting platonic form as it were. Geometry, while being a priori - is just one system among others, which informs our perception of the world but doesn't have to. Different humans can build a different system of concepts to interpret the world by.
I don't know a lot about this but Strawson goes into it in "The Bounds of Sense" I think. The relationship of the senses to the Kantian system of perception.