Different points in time/universes. There is saturn girl from 247 AND the Disco era. Same with cosmic boy. There is Pre-crisis Supergirl who may be from the New Earth One or could be the actual pre-crisis Supergirl escaping from Time trapper's retcon of her.(which is my speculation but it fits with 'erasing the superman legacy'). There is threeboot cosmic boy who was in Earth Prime's 41st century.
Also Tellus is free from Cadmus now. I think he's still around though, making sure Mon-El doesn't endanger his future with the Legion.