Matrix especially didn't work after the whole Pocket Universe Superboy was removed from canon. Where did she come from if that story never happened? How hard is it to find some other planet like Krypton and just have her be a refugee from there?
I don't see Returns as being part of the Donner series. I see it as a wholly separate universe where some things happened the same. The costume alone kind of kills the connection. Taken in that context, it wasn't that bad. I still liked it better than MOS.