When Copying/Pasting Text in Apple Numbers, it often creates too many columns, using what feels like random separators. The result is sometimes hair pulling...
Now there is a way to adjust things, but it is not obvious, and you have to be quick to spot it because it quickly disappears unless you click on it right away.
What I'm talking about is the "Table data was imported and can be adjusted." Pop-up Button.
Once you click on this button, you are presented with an Import Settings window in which you can tweak a few things, including how many columns you want in fine. Very useful.
Here is a screen capture sequence so you can see how it works: