It's a "fact" that the kids at Garabandal were levitating backwards up steep hills. It's a "fact" that someone found a piece of heart tissue somewhere. But is the devil incapable of creating levitation, obtaining a piece of heart tissue, and putting words and visions into someone's mind? Clearly not. So before we begin speculating on what "God" might be trying to communicate here, that conversation needs to go hand in hand with what the devil may have been trying to accomplish with this.
To me, the following scenario of a diabolical activity is just as likely as that God was trying to tell us something.
Let's assume that the New Mass is invalid and/or displeasing to God and that Bergoglio in his activities as Francis is not pleasing to God. But in order to cast doubt on this, the devil concocts this miracle in order to get people thinking that the New Mass might be valid/pleasing to God, that Bergoglio might be a holy man after all, that Traditional Catholicism which criticizes both the New Mass and Bergoglio might be false, and that Bishop Williamson should announce publicly to people that one might attend the New Mass under certain circuмstances. In that case, mission accomplished for the devil based upon the replies we see on this thread. Lots of damage done through the simple act of finding a piece of cardiac tissue somewhere.