The CQ User guide does not specifically say if the FX sends are post fader or pre fader. However based on your experience, I think we can assume they are pre-fader. Therefore the signal is going to be sent out to the various outputs based on the “send levels” and not based on the FX fader level. Pages 47 & 48 of the user guide talk about the FX in “shared mode”.
EDIT – actually the pre/post performance is likely set by the Input Send Levels (page 62 of the user guide). If your aux output is set to pre fader (which is likely if it is being used as a monitor feed), then all of the inputs levels would be pre fader, including the FX signal. What the system doesn’t seem to allow is to change the pre post fader choice “per input”. Rather it seems to be a global setting.