User blog comment:MakeShift/The Crisis and its impact on the Arrowverse Wiki/@comment-31524712-20200124154231/@comment-26537965-20200129225613

Just because Lucifer has never mentioned Constantine, it does not mean it did not happem. The idea of him having a history with Constantine was not invented yet back then, so no wonder there was no mention of Constantine. It could still have happened considering it seems interdimensional travel was a thing in the new multiverse too, since Laurel-2 is on Earth-Prime.