Hi, I'm on
Minecraft: 1.21.1
neoforge: 21.1.133
createoreexcavation: 1.6.3, 1.6.2, 1.6.0
KubeJS: 2101.7.1-build.181

I'm getting the following error for e.g. the example code from #131 :

[main/ERROR] [KubeJS Server/]: server_scripts:main.js#5: Failed to create a 'createoreexcavation:vein' recipe from args [{"text": "raw tin"}, mekanism:raw_tin]: Constructor for createoreexcavation:vein with 2 arguments not found!
[main/ERROR] [KubeJS Server/]: main.js#5: Error in 'ServerEvents.recipes': dev.latvian.mods.rhino.EcmaError: TypeError: Cannot find function placement in object createoreexcavation:kjs/3kkgyrgdo34mqk3sfjq4b8a1p[createoreexcavation:vein].

Seemingly KubeJS cannot find any two-argument constructor for event.recipes.createoreexcavation.vein, despite all examples pointing to that usage. (I might parse the error wrong potentially, I know very little about KubeJS's internals)

I am having the same issue at the moment, if you find a fix please post it!

KubeJS support isn't in the 1.21 version yet. (It's planned once Create has it)
You can copy the jsons out of the mod and create a datapack:
https://github.com/tom5454/Create-Ore-Excavation/tree/main/NeoForge/src/generated/resources/data/createoreexcavation/recipe/ore_vein_type