Adding recipes to the saw does nothing

After not having any documentation and therefore guessing by peeking at the source code of this mod, I tried to add this recipe:

onEvent('recipes', event => {

event.custom({
  "type": "mekanism:sawing",
  "input": [
    {
      "item": "minecraft:saddle"
    }
  ],
  "mainOutput": {
    "item": "minecraft:leather",
    "count": 6
  },
  "secondaryOutput": {
    "item": "minecraft:iron_ingot",
    "count": 1
  },
  "secondaryChance": 0.5,
  "energy": 2000
})

}) //onEvent('recipes'

There is no error message and there is no recipe assigned to a saddle.

KubeJS-Mods / KubeJS-Mekanism

Adding recipes to the saw does nothing #3