GIMP developers hope to move entirely to GEGL by version 2.10.
One of the major advantages of GIMP using GEGL is the ability for non-destructive editing and high bit-depth images.
GIMP now only saves to its own XCF format to retain layers and other file manipulation information. Its developers are taking the user experience into serious consideration and are speeding up development for this already great photo editor.
Users can still choose to save in formats like JPEG and PNG but will have to "export" the project instead of saving.
But you already went into the script folder so you don't have to worry about it really.
You'll have to wait for ofnuts to see what he can make of your latest gimp-message dump posted above.