The docs are a little confusing/sparse on leveling Z. I ran into the same problem (may actually want to start one post earlier in that thread where I shared my initial confusion.)
This process was key to me figuring out what I was missing:
Was the part that I kept getting confused by. I assumed it was just reading the Z position off in the fluidNC interface (Though - I know that’s not what @Tokoloshe is doing since he’s all in on Estlcam as a controller.) The video was key to me realizing that the probe command returns the Z position in it’s output so you can just read it from the log - then work out the new pulloff for whichever side needs adjusting.