At the time, we had no idea as to authenticity of those titles, but James Cameron has now spoken out about them, and it turns out that they are real titles, however they are only real potential titles.
James Cameron is in the middle of a massive undertaking as he continues work on two of what are planned to be four more Avatar movies.
We know little about them overall, but we were given a possbile hint recently when titles were leaked that purported to be the planned titles of all four of the upcoming sequels.