I agree, a prime plugin candidate. I would suggest one modification though; if you have 117 scenes, such a plugin would generate 117 new layers too, wouldn't it? Perhaps it would be better to hide the new text in all other scenes by updating their Hidden Geometry settings somehow? Also, if you are doing all the documentation last, perhaps the script would also jump the the next scene and continue when each text box was complete, with the option to skip a given scene or quit at any time (GUI buttons or shortcut keys, perhaps?).

I'm actually surprised that SU doesn't have an option to have screen text visible only when on the scene it was created in, or only a chosen scene, etc., but I suppose it would keep disappearing every time you moved the camera even a little, which would be infuriating when adjusting a given scene. I suppose hiding all but the appropriate text for each scene would be best.