I have actually been playing with this it's pretty cool.

You create a python script using input for different ingredients.
Fooling around i actually created one that takes a selection and copies and pastes it as a floating layer.I am still trying to figure out how to create a new layer from the floating selection so it could be a useful script.
Then the user could just make any selection on the image - Go to shortcuts/copy-selection
The selection would be copied, pasted as a new layer in place with (no floating selection).
Guess it is already a part of Gimp but i am just fooling around seeing what i can do.That seemed to be the easiest script to start with.

The only real useful part of the script would be the floating layer - you wouldn't have to anchor it yourself. (lazy i know)

- But like i said i am just fooling around with it.
Anyways its pretty fun to mess with.I tried to create one with Lyles Soft Focus settings for GMIC but there was an error calling the plug-in for the script.Still have to figure that one out.Something to do with the GMIC command i am sure.