Could be a working title, but I doubt it's the finalised one.
Well it's not like some of the original trilogy's subtitles were vague,
Attack of the Clones was actually a pretty good bit of misdirection, because nobody which expecting which side they were on.
The Phantom Menace actually threw me off more because at the time it was released, I erroneously assumed it referred to Darth Maul, since he was the Sith Lord who revealed himself to the Jedi after the Sith were believed to have been extinct for a thousand years even by the Jedi themselves, when it actually referred to Palpatine and the fact that he was really the Sith Lord manipulating his own rise to power. Since I never got into any of the novelizations or Expanded Universe shit, I had no idea that the Emperor from the original trilogy was the same Palpatine who served as Senator from Naboo and later Chancellor of the Republic (or even the fact that his name was Palpatine for that matter), or that said Senator/Chancellor Palpatine was in fact the same Darth Sidious who was manipulating the Trade Federation and the Separatists. I simply assumed Darth Sidious was the OT Emperor, but about 2 weeks before the release of Revenge of the Sith, I visited the Star Wars website, I saw the Palpatine article confirm the Emperor's identity to be Palpatine, while Darth Sidious's article was separate and vague, since they were treated as separate characters at the time (likely intended to avoid spoiling ROTS pre-release). I managed to make the connection based on my initial conclusion of "Sidious is the Emperor" when I read both articles, but in the process I accidentally spoiled ROTS for myself...and I saw that film at the midnight screening on release day. The fact that "OT Emperor", Senator/Chancellor Palpatine, and Darth Sidious were all portrayed by the same actor (Ian McDiarmid) should have been a dead giveaway for me to connect the dots from the very start.