In KoTOR when Carth said hell I felt that was strongly out of place. Since this is Star Wars they should have created their own word for hell like you said they come up with their own versions.
Speaking of which, I always found it a bit... disorienting when Han says in ESB "I'LL SEE YOU IN HELL!" It just seems so out of place...
I guess the best explanation would be that the masses of the galaxy have some religion where a hell and heaven type place exist. The concept of the force is usually limited to the Jedi, and those who do know about it think it's make believe ( like Han and Jar Jar ). Of course, that then wonders why the word hell would still exist and not have their own word.