Haha, that looks familiar!
When I originally conceived of my bracket design, I decided to use the single center hole for the pulley for attachment. I didn’t want to bother the left/right extrusions when attaching and removing it, and end up needing to readjust anything.
If you pull the bracket tight to the bottom of the z-axis plate and tighten the pulley screw/nut, the bracket doesn’t budge. I’ve been using mine for some time now (since about April I guess).
I like a shoe with a bit slot, it makes removing/replacing easier.
I also have added very short (1/4" high) skirting right around the edge of my shoe’s bottom hole, and I can adjust height so it just hovers above the top of the material. Nothing escapes.
Someone should crank-out these brackets and sell them.
OH AND I NOW see your holes for the threaded rods coming from the shoe aren’t slots. If you make those slots, your shoe will go on and come off much more easily.