Because there's no way to confirm this without a screenshot or video of the cast. And the films are listed like it is in the credits. And if it's on a FUNimation page you shouldn't bother, it's the worst source because everyone can't see their content. That's why many FUNimation projects aren't on this wiki.
If I had still runned the previous voice acting wiki (Animevoiceover wiki), I would have been more strict with the users there as well.