What are the sliders like on the CalSynth clone? Ie the degree of resistance... I truly despise sliders without a decent bit of torque needed to move them (I'm looking at you, Grandmother sustain slider).
You can find some "clones", but most of them are "half veils":
https://www.modulargrid.net/e/calsynth-2vca
https://www.modulargrid.net/e/after-later-audio-dvca-
If you are going to have 4 VCA's, definitely choose a "in cascade" module like Intellijel quad vca
https://www.modulargrid.net/e/intellijel-quad-vca
-- ferranadsr