Discovered this while trying to stage tipped arrows.

It seems that setRecipeStageByRegex looks at the recipe key, not the "name" of the item as returned by /ct names. This causes a fair amount of confusion. Using tipped arrows as an example:

The name is: <minecraft:tipped_arrow>.withTag({Potion: ""minecraft:night_vision""})

The recipe is: recipes.addShapeless("minecraft:tippedarrow", null, []);

There doesn't seem to be separate recipes for the arrows, though I can see them in JEI. There must be somthing special about how arrows are crafted. Regardless, by using the value returned by /ct names, it would not only clear up confusion with "tippedarrow" vs. "tipped_arrow" but also allow staging based on the type of potion on the arrow.

The regex removal only works because it looks at the registry key, no good way to do it on the item name.