In FCPX 10.4 In the keyword shortcut dialog box, numbers 1 to 5 are missing?

No, you delete the application's preferences as a whole.

That is not a big deal, since, as you can easily check, there aren't many preferences to set.

Start FCP while holding down command and option, and click "Delete Preferences".

You will then need to reopen any libraries you were working on, and go to the Preferences and set them as you want them.

Corrupt preferences are known to be the cause of many weird problems, and this procedure is usually one of the first things to try when something in FCP X does not seem right.

Missing how? The numbers do not appear, or the boxes themselves do not appear?

You may want to try deleting preferences and see if things go back to normal.

Did you try deleting preferences?