Darth Maul calls himself a Sith lord every time he calls himself "Darth." "Darth" is the title of a Sith Lord. You don't have to be the master to be a lord. http://starwars.wikia.com/wiki/Sith_Lord
The Sith race is no longer canon. However, even in Legends, they were so far removed from the present day as to be irrelevant. Sith as a catchall term for dark side Force users is quite explicitly wrong. Snoke and Kylo are dark side Force users, but not Sith. The Nightsisters are dark side Force users, but not Sith. Yes, the Sith organization was named after the Sith race in Legends, but the part that survived was the organization. Not the species.