These ones stood out as may be stretching it a little.
Cliffhanger I would think is just a name sorta like WWE's Backlash where (at least for the first couple of showings) the matches on the card or angles on it are direct results of previous actions, generally from matches and such from WrestleMania in Backlash's case. Themes for booking PPV's help sell in real life, even if they aren't because of a match type like the Rumble or Survivor Series. Cliffhanger as a PPV name suggest that there will be a cliffhanger, an "omg whats gonna happen next" ending.
Ground Zero does not equal WTC locations, well not exactly. Ground Zero is a term for the place an explosion occurred. Though it also is used for natural disasters, diseases, epidemics or any disaster that has a radial spread. Ground Zero is the center point of the most destruction or initial point of origin of occurrence, which are generally the same place. Ground Zero would have the highest value of damage/viral spread or what have you. So while the location of the devastation at the WTC has a Ground Zero it is not THE Ground Zero. The term was first used in the media describing the area under where the atomic bomb exploded at Hiroshima. The use of it for the article came from the fact that it was slang in the military for the detonation place of the first ever nuclear weapon test at the Trinity testing site where the tower housing the nuclear weapon was at "point zero" on their grid.
Dog Days, I'd say comes from the term Dog Days of Summer, which refers to the high heat period between July and September in the Northern Hemisphere. Also used to describe events or time frames that are dull or with nothing getting done. IE just sitting trying to get cool in those hot months. I actually know more about the etymology of the term Dog Days but I doubt anyone on here really cares. So I'll leave it at that.
Sorry I'm a huge history and etymology buff, and of those Japanese culture/history and WW2 are my favorite areas.
Though thats not to say you aren't right, these just seem more plausible to me. They make very sound Event names (even outside of wrestling) just due to the definition of the words themselves. They give a sense of what the show is about. Or in the case of Dog Days the time of year it occurs, hopefully, cause who'd go see a PPV where the title suggests not much is gonna happen/be dull.