Its a very interesting question and a number of people have asked similarly. SFAIK there are no articles and Jussi has not given many details. We did, however, recently learn that the DAC corrections do correct some roll-off in high frequencies with the Holo Audio Cyan 2:
Best native DSD DACs for use with HQPlayer? - #2298 by jussi_laako
Accordingly, my understanding is that the HQP software is not detecting DAC errors, but the corrections are calculated by Jussi after measuring various DACs on his bench. I believe the DAC corrections are similar to a convolution file, but others have speculated they are associated with modulation.