The Civilians of planets such as Coruscant and Dantooine propably started the name Jedi Civil War because it did start amongst Jedi. Ulic, and Exar Kun were Jedi that turned to the dark side and became Sith Lords. However I haven't heard much of a dark jedi saying, "Stop calling me jedi! I'm a sith!" or something like that. So it is only fair for people to know them as Jedi.