“But availability for empirical experience depends on superimposition” (pg.419 numbered section 142: The Method of Vedanta by Sri S.S.S.)
Even though the Swami is talking about mutual superimposition of the Self and the non-self I think that a tangential truth is expressed about what Vedanta Paribhasa calls perceptuality. In other words, superimposition is the fact whereby the stone out there as an object comes in some sense to be in me, the subject.
Why do we not take the experience in here as a bounded subjective domain in the manner of Idealists (both subjective and objective) and Representationalists/Scientific Realists? Because for Vedantins the Vedas have an intrinsic ‘aboutness’. The language that they are expressed in is eternal, capturing, for all time, and in every eon, universals (vedic words). The action of the enjoined sacrifices is real and effective.
Starting from that foundation a metaphysics is promulgated which can sustain the non-numerical identity of object and mental modification (vritti). In his own way Aristotle squared that circle also.
What about illusion? Does that not break the upadhi link? It was a witty metaphysics that used as a founding analogy the fact of error. It is still the case though that our default assumption is of perception as veridical. Further experience may prove us wrong and we can accept this. We may even test our experience in an experimental fashion: Come let me clutch thee/I have thee not and yet I see thee still. Our realism is critical (krites/judge).