That's just their naming convention not any kind of official title of the game. After all they do "Bard's Tale, The" and we do "The Bard's Tale".

Imagine these games were being submitted to the Library of Congress. How would the names be determined? Is there an official cataloguing kept by the publishers?

Not as straightforward as you might assume.

I can often cross-reference Mobygames with Wikipedia and the official title of a game will be different. Hell, sometimes the article name of the game on Mobygames is different than what the description reads.

A colon? Or or no colon?

Nickelodeon Avatar: The Last Airbender?
Avatar: The Last Airbender?
Nickelodeon - Avatar: The Last Airbender?

Burnout Revenge or Burnout: Revenge?

Is it SVC Chaos: SNK vs. Capcom

or is it really

SNK vs. Capcom: SVC Chaos?

Another example is 2005's "Area-51" which clearly has a hyphen on the box cover art but on Redump it is just "Area 51".

.. and so on and so forth. How is this decided? I've seen some subtitles/bits added on to game titles that don't even show up in th main menu/screen.