Ok, so I noticed the same issue mentioned with black levels when I used an original raw file, and the issue is present but hot pixels get fixed regardless of if the subtraction file is the ‘real’ one or the averaged ‘cludged raw’ file, so my intuition tells me that it is an inevitable quirk of the darkframe subtraction with the BMPCC, based on elevated effective black levels. If this is true, then I should just continue to add the negative black point compensation in the raw tab after enabling subtraction. But the other less plausible but still possible option is that the black point in metadata manually inserted for the subtraction frame is not correct and I should continue fiddling with it. I was just curious if you had any opinions any one way or the other.
Nonetheless, I got the pseudoraw darkframe effectively working, in large part thanks to your much appreciated guidance, and question posed above is more theoretical minutia about the most optimal way of doing things than technical obstacle of necessary surmountation.