"Some" does not mean that's the foundation. There's far, far more of his old history back including the origin that it is the clear foundation. And even then, a lot of those early references don't make a lot of sense anymore and could easily fade away. With Superman Reborn, they worked a couple elements into his pre-FP history. NOT the other way around. Supergirl is different, which frankly makes the lore a mess because she's intrinsically tied to Superman. But, a lot of things are still a mess. But Superman aside, DCU-wide the clear pattern is N52 discrepancies defaulting back to the pre-FP reality. Its been going on for two years now and its hard to imagine that not continuing till they get to the point of being done tinkering (in general), be that after Doomsday Clock, or with their 2020 event, or whatever.