So is Lenas back in/only in ep 19? Maybe.
“Lena Luthor confronts Beth Breen, a CFO from a rival company that takes
over the rights to a nano swarm technology. The technology can heal very
injured people but has a side effect of removing free will. Beth Breen
can take control of anyone that has been injected by the nano tech which
makes her a kind of queen bee to the swarm! Right now, we believe this
event is for episode 19 but could be 18 or 20(…)” - SUPERGIRLTV