I would tend to think that someone as focused on production as Bach was, and by that I mean finished pieces, he probably knew exactly what he was creating as he composed it, whether he was playing it backward or forward. It doesn't surprise me that it works either way
and it works together. I am not musically trained beyond the rudiments, nor am I an academic on Bach, but I do understand the musical creative process well enough to know that trying things out backward is part of the fun of creating music. Musicians were doing it long before The Beatles did.
