Thanks for sharing. I'll be sure to look at it more in depth, I just noticed it now.
I used to take a bunch of different classical pieces and invert the whole thing, a full retrograde invert. Meaning Beethoven-flipping-the-sheet-music-upside-down style, then transpose all the parts to their registers. From there you may need to make a few bass adjustments, but you have all kinds of new upside down music awaiting you, and lots of it is good. I think Beethoven did some of that too, in his symphonies. His 3rd for example, has a number of melodies the same upside down. The rules are different in the parallel universe though :)
Some compositions I will work back and forth between both dimensions. Flip the sheet music over, write some more to fit that end. Or invert without flipping. Thy become different shades, constantly weaving things into new colors and possibilities.