As suggested by @Alastair on Ability to create composition-local subcompositions...
Currently, when you make changes within a subcomposition, the changes apply everywhere the subcomposition is used (every instance of the subcomposition as a node in a composition).
This feature request is to add the option to edit an individual subcomposition instance without affecting others, and without future changes to others affecting it.
There's a bunch of situations I'd use that in. Personal Text Layer nodes where I want to use something I've got already got going but then tweak it inside a bit to do something else, like round off or smooth a number value input that's irrelevant to the original sub-comp/macro I copied it off because it doesnt have a separate numeric value input...
Thinking that through some more, you might want that library or 'node class' kind of subcomp to be universal, either local comp constrained or global for all Vuo comps that user has, and the way they drag it onto the graph determines if it's local or global in scope. Holding "Option" key while dragging from the Node Library or hitting "Enter" key while selected in the Node Library makes it global for instance.
Clicking Period Key while cursor is over a 'node class' subcomp devolves it into a simple macro environment with no implications on other instances when it's changed inside. And vise-versa dumping any internal changes when returning to an existing node class.
Would need some kind of subtle UI indication of scope i.e. itself/local-composition/global.
Square corners ⇒ isolated; round corner ⇒ local sub-comp; chamfered corner ⇒ universal sub-comp.