I hope I’m understanding correctly: You shouldn’t be trying to mix your aliases into the ‘stonehearth’ manifest. Your mod has its own manifest in its main folder. This will automatically be loaded when you run the game, and its where you should put all of your aliases.
The reason you’re getting that error is because ‘stonehearth’ the game’s main ‘mod’ doesn’t have your item in it. You’ll be better off adding your item to your mod’s manifest and leaving the base game files untouched.
Have your previous mods worked? As a suggestion, @honestabelink had put a nice tutorial up a few months ago. If you haven’t made a mod before, it can show you how to add a basic item, from which point you can tinker and find out how to make it a ‘fine’ item: