I dont know which part doesn;t work but one of them doesn't because the recipe doesn't show up in jei nor when you pit kiln it,
in startup scripts I have this:
onEvent('server.datapack.first', event => {
event.addTFCMetal('genesis:molten_tsalachtite', 800, 75, 'genesis:tsalachtite_ingot', 'minecraft:iron_ingot')
})
and on server scripts I have this:
onEvent('recipes', event => {
event.recipes.tfc.alloy('kubejs_tfc:genesis_molten_tsalachtite', [
['tfc:wrought_iron', 0.35, 0.3],
['tfc:zinc', 0.65, 0.7]
])
})