Making Material Function behave like native functions?

So iam trying to turn my material functions into native functions to call them easier across all my projects.
I copied it into Engine/Content/Functions/EngineMaterialFunctions01/…
but no matter what, i can not call it from the material editor this way.

I tend to write general stuff into Functions, so it would be nice to get a function somewhere inside the engine to make a function native.

You have to expose your Material Function to the Library. In the MaterialFunction Settings you have checkbox for doing so (Deselect the current selected Node to see the Material Function Settings)
I do not recommend putting your own Material Functions into the Engine Folders, since it won’t work anymore if you migrate it to another version.