I wouldnt mind if the code in the txt files wasnt changable in GE. So long as they were .txt fiels you could open them in anything (notepad etc) and edit your code, then just copy those files into however many project folders you want to affect.
My point about not wanting to copy and paste is because you need to copy the working code into say notepad (or the clipboard), then load the new project, select the actor or go into global code, select the relevant section then delete whats there and paste in the new code. You might need to do this multiple times which takes a long time and is a real pain

Imagine just updating the one txt file, loading up your game and hitting export knowing that the code had auto-updated!