Deleted. linking a rack 1 video might confuse things. Mostly valid for rack 2, and worth a watch.
Rack 1.1.6 video
https://www.youtube.com/watch?v=hYdZVfL_8fU
jump to 32:00 for key tracking filter cutoff
Jakub used the VCV Unity module in his patch, It’s available in 2.0, but only after tweaking.
VCV VCA-2 module not updated to 2.0+ - #2 by contemporaryinsanity