I've been trying to think about what exactly the relationship between conceptual and nonconceptual error is for Dharmakīrti. So we know that all perceptions that are structured by subject/object duality are erroneous (even though they're nonconceptual) with respect to the fact that they present the existence of an external object that is separate from the subject. The other nonconceptual distortion is that things look permanent (or at least not momentary).
But (I think, and here's where things get a bit murky) perceptions are also NOT erroneous with regard to the causal characteristics of the particulars involved on a whole slew of other things. If I'm cognizing the appropriate set of mental impressions to give rise to a perception of my cat, that perception isn't erroneous qua cat; it's just erroneous insomuch as I'm interpreting the unique particular that is the mental image containing the causal properties necessary to produce a judgement "hey, it's mrphball!" as being some enduring external thing. The only reason that perception and inference can function at all is that there are some aspects of the cognitive image that correctly track causal properties of the particulars that produce it.
But how far does this correct tracking go? Another way to ask this question would be, what appears in svasamvedana? My normal, samsaric perception of my cat is nonerroneous if I'm actually able to interact with her, etc. Does the nonerroneous part of this image STAY nonerroneous at the ultimate, svasamvedana level? Or is there some kind of radical discontinuity between the parts of perceptions that are nonerroneous conventionally and the parts that are nonerroneous ultimately? If I were to svasamvedana mrphball, would her causal characteristics still appear in some nonintentional, nondistributed way? Is that just prakāśa? Is that prakāśa different from the prakāśa of a cognition that would conventionally lead to a perception of my bike? What does it mean for the prakāśa of a particular svasamvedana to be different from another prakāśa? If they're all the same, why do we have cognitions of different things? If we have cognitions of different things because of error, how can we account for the many different nonerroneous parts of normal perception?