A number of shows, particularly those from Britain, do not have episode titles. The "official" titles are simply Episode 1, Episode 2, etc. This is a fine for the chapters of a serial, but becomes problematic when trying to figure out which episode is which for a long-running show like Spooks or Death in Paradise. So when these shows are packaged for syndication in America, episode titles are typically added. These titles are not made up by fans, but as I understand it are typically derived by looking at the original scripts or consulting with original authors. Sometimes the authors have come up with clever titles for their stories, and are glad to see these restored.
The policy here at TVMaze has been to ignore these new titles completely, and to delete them if someone tries to add them. I think this is wrong, and that these semi-official titles provide useful information that should not be discarded. We already know that they are Episode 1, Episode 2, etc. because we have them numbered. No information is lost by adding these AKA titles in place of the generic ones.
I know that some of you are perfectly happy to refer to an episode as S06E05, but whenever there is confusion, it is helpful to have an actual episode title. It also makes the episode list a lot less dull.