KHN active filter design
The KHN (Kerwin, Huelsman, Newcomb) biquad schematic was quoted ref 1998 has the wrong schematic for your formulae.  It was originally published by KHN in 1968. I used it successfully 10yrs later.  It was written before 1995 yet published in 1998 with the positive feedback input then changed to the inverted version in 1999 by Deliyannis et al yet the older version was requoted  here, I believe in error in a great textbook by and then required by too many who failed to recognize the differences to make the BPF output non-inverting.
Fortunately there is some historical analysis done by Soliman on Researchgate in 2008 (TL;DR) here which may clear up your confusion of formulae and 2 different versions.
From a casual look, you are correct to assume the results are incorrect and the R1/R2 ratio is good for more than 100 dB attenuation.
Try the inverted input version or if you prefer, figure out how citations got screwed up without corrections.
If anyone has corrections to my comments , feel,free to edit if you know better.