Thank you so much, Feniks.
I don’t know how to explain this, but basically what happened was that I deleted the 'color_picker_example.rpy' file, but its compiled version (.rpyc) was still there and in use. So when I was looking for 'Return'to edit, I was searching in the wrong file all along!
Sorry for wasting your time with such a noob question, lol. Thank you so much again for your time and for this amazing tool!
Oh and thank you for the shift + I tip! This is the first time I've learned about it, such a helpful feature!