I think the equations should read like this (the signs are reversed):
RFB >= (0.25V / Vexc) * (1 / PGA) * Zmax
RFB <= (3.2V / Vexc) * (1 / PGA) * Zmin
For example, if my output excitation voltage is 0.2Vpp, PGA is 5, Zmax is 1689 Ohm and Zmin is 762 Ohm, my RFB should be between 422.25 and 2438.4 Ohm since the recommended RFB (from AN-1252) is 2212.7 Ohm.
I also noticed that in the Miguel's equation you gave, https://ez.analog.com/message/109800#109800 , he stated that Vexc is excitation frequency, but I believe it should be excitation voltage, isn't it?