No, I’m definitely being more descriptivist than causal-ist here. The point I want to get at is on a different axis.
Suppose you were Laplace’s demon, and had perfect knowledge of a human’s brain (it’s not strictly necessary to pretend
determinism, but it sure makes the argument simpler). You would have no need to track the human’s “wants” or “beliefs,” you would just predict based on the laws of physics. Not only could you do a better job than some human psychologist on human-scale tasks (like predicting in advance which button the human will press), you would be making information-dense predictions about the microphysical state of the human’s brain the would just be totally beyond a model of humans coarse-grained to the level of psychology rather than physics.
So when you say “External reference is earned by reasoning in such a way that attributing content like ‘the cause of this and that sensory state …’ is a better explanation”, I totally agree, but I want to emphasize: better explanation for whom? If we somehow built Laplace’s demon, what I’d want to tell it is something like “model me according to my own standards for intentionality.”