What Konnikova meant by the phrase "Caveats don't fit in single columns" is that unclear headlines can misdirect readers.
A caveat is a warning. Given the context of the statement by Konnikova, we can interpret the statement to mean that short headlines can mislead readers.
When readers do not really go into the depth of a speech to determine the full information, they could be misled.
Learn more about headlines here:
https://brainly.com/question/943780