I think I have managed to do what you wish to achieve, there was not too much detail in your request. Have a look at the video filr.microfocus.com/.../macro.mp4

Write a macro to do what you wish, I wrote (Well ChatGPT did most of it, but made a number of mistakes) a macro that found the first table in the document, went down the comments column until it found a blank cell, then inserted the current date in the date column.  I found the word macro did not work in CE so I ended up doing it in LibreOffice.  Do edit the macro as necessary.  

Sub FillDate()

                Dim oDoc As Object

                Dim oTable As Object

                Dim i As Integer

                ' Get the document and sheet

                oDoc = ThisComponent

              oTables = ThisComponent.getTextTables()

              oTable = oTables.getByName("Table1")

                ' Loop through the rows of the table

                For i = 0 To  oTable.Rows.Count - 1

                                ' Check if column B is blank

                                If oTable.getCellByPosition(1, i).getString() = "" Then

                                                ' Fill in the date in column A

                                                oTable.getCellByPosition(0, i).setstring(Format( Now, "DD\/MM\/YYYY"))

                                                ' Exit the loop

                                                Exit For

                                End If

                Next i

End Sub

Set the macro to auto run when opening the document.

Enable Macros in Content Editor as per the Collabora documentation at https://www.collaboraoffice.com/integration/how-to-use-and-manage-macros-in-collabora-online/ For security reasons I left the run macro prompt in, you may wish to go for a security level of 0 so there is no prompt.

When I open the document the current date is inserted in the date column,

Oh my! Thank you Robin, I will test this tonight,