Used the example scripts for adding custom recipecategories.

Error in 'JEIAddedEvents.registerCategories': ReferenceError: "guiHelper" is not defined.

jei-1.20.1-forge-15.20.0.106
kubejsadditions-forge-4.3.3
1.20.1-forge-47.3.12

I just updated the README example to what I think should work.