@BitBob, I wrote a little python script to massage the JSON calibration file as by your suggestion, see here:
massagecal-anonymised.py (688 Bytes).
Indeed those filter settings seem to achieve the goal without obvious negative side effects.
Digging deeper into the settings, I see that the higher order filter coefficients (coef[2], coef[3] and coef[4]) all have b1 set to 2 and b2 set to 1. Isn’t that dubious in the first place?
Btw, I found that in my case a groupDelay of -1 would be more appropriate for the simplified filter channel at all sampling rates (although for 781250 and 1562500, groupDelay of 0 and -1 were a tie).