Adding column to multiple identically formatted tables in Numbers
I'm not sure I understand your question exactly. But, if all of the tables are on one sheet, and all of the tables need to get the same new column and the same column title, this will work.

Screenshot of Numbers document with three tables on the sheet, before running the script.

Screenshot of Numbers document with three tables on the sheet, with column added and titled

Here is the AppleScript that adds the column and names it.

tell application "Numbers"
    set theTables to every table of active sheet of document 1
    repeat with aTable in theTables
        set myColumn to add column before column "B" of aTable
        set value of first cell of myColumn to "Birthplace"
    end repeat
end tell


A few notes-- you can add a column "before" or "after." Also, you can refer to a column by the letter atop the column, as I did here, but you can also refer to a column by the label in the Header row. In this case, that would be Column "Month".