If any show or movie is missing from the database, anyone can add them on TMDB and import them on Trakt already.
Just copy the ID of the page on TMDB and in the footer of Trakt there is the option to import them.
For more information on how to do that, you can check these 2 topics:
How do I add a missing movie? - Support / Tutorials - Trakt Forums
How do I add a missing TV Show? - Support / Tutorials - Trakt Forums