That's so cool! I knew about how the original Supergirl/Legion story made the then-common time travel mistake of thinking that since time had advanced in the present (Superboy's time to Superman/Supergirl's time) then the time in the future also had to advance leading to the children of the originals bit, and how that backstory was quickly dropped, but I hadn't realised that it was changed in the first reprint 6 years later.
I also hadn't realised that they rewrote that line from Jo that he was restricted to just his visions powers.