I think it should work if he mixinto the recipes his file with this content:
{
"produces": [
{
"fine": "your_mod:decoration:your_fine_item"
}
]
}
If it didn’t work, maybe it is because of the array? (square bracket) In that case we would need that “mixintype_given_names”:“override” as explained here: [A17-3008] Overrides in mixintos