Thoughts:
I heard HH was the first song written for a more OOTB-sounding album too but I guess she changed her story retroactively. Part Of Me leaked around Firework's single release and was rumoured to be part of a reissue even then, back in 2010. I remember waiting so long and thinking it was cancelled and then two years later, it happened.
I'm really glad she didn't take Titanium or Elastic Heart, she wouldn't have done them justice + she didn't write 'em. Double Rainbow never should have made PRISM though. PRISM definitely would have been rereleased if the era was more successful. It would have gotten 6 singles again too.