Hi! I've done two big albums (Backside Front, Static) and hours of unreleased synth music using ZASFX, and I use it for everything for years now. I love it.
I think ZynAddSubFX needs to change the numbers displayed from the arbitrary range of 0..127 for each knob to some more sensible, context values including unit symbols like 200 Hz, -15 dB, 302 ms, L30%, R78%, -23 cents et caetera.
It would make things a lot easier for both brand new and stone hard users like me.