Kieran,
It's long been my sense that what the church's leadership wants is a free pass for all of the bishops in power (at least up to some unspecified date), and then they'll consider addressing accountability after that.  The unspecified date would likely (and conveniently) kick in after the last of that generation of bishops die. I know that sounds like a horrible thing to say, but I can't come up with any other explanation as to why we've seen such inaction in the face of so much anger, hurt (etc) within the laity and public. The logic behind this seems an almost laughable sense of "how could we know...?"  In secular law, we'd be seeing a string of negligence cases all the way to the horizon with this defense.  

That retroactive Canon Francis might have had to create, reminds me of the principle of "equity" under secular law.  And it's interesting that on something as basic a human morality issue as is this, the the church won't go there, even as secular at least tries...