Kevin actually uncovered a pretty big bug in the detection and interpretation of discrete parameters (probably mostly in JS FX). Anyway, it was easy to fix it. With upcoming ReaLearn version you won't adjust continuous "step sizes" anymore for most JS FX parameters but instead discrete "step counts" - because most (or all?) JS FX parameters actually have discrete integer numbers as values. This is very useful for fine-tuning. One relative increment with your rotary encoder (or button press) should result in exactly one increment of the JS FX parameter if you have step count 1.
Issue #151 resolved