If you’re arguing that we build an internal model of our environment based on raw data from the sense organs, then I’d agree. But that doesn’t mean that simultaneity and continuity are “illusions”, since we’re talking here about how we experience the internal model, and not about the functioning of the nervous system, or whatever. Our physiology is designed to present us with continuity and simultaneity, it enables us to make sense of the world.
In any case, Buddhist psychology is not concerned with this stuff, it’s concerned with the conditionality and instability of our experience. It’s concerned with what we experience in the mind, and not with nerve impulses or whatever.