Just a heads up, ACE - Authorized Community Expansion Project is working on a Magmasmith also, as a Dwarven-kingdom exclusive upgrade to the Blacksmith. You’re welcome to join the project or continue making your own version.
As for your error, magmasmith_hammer_recipe.json
is including magamsmith_mod:
in the product alias, when you shouldn’t be specifying your mod’s namespace in your own aliases.