In case some column in range A:F has unique value for for table row, define the datarange of this column as dynamic Named Range (e.g. nTableRowID). Otherwise add a column with formula, which creates such unique identifier for every table row, and define the datarange of this calculated column as dynamic Named Range (e.g. nTableRowID).

Now in another sheet, create a 2-column table, where for 1st column you define Data Validation List, which allows you to select a row inentifier value from main table (using defined dynamic Named Range as source (e.g. '= nTableRowID'). Select the row identifier value in 1st column, and enter comment for this main table row into 2nd one.

In main table add a column to display comments, and fill it with VLOOKUP formula to get matching comments from 2nd table for every row.

Now when you have next update of your main table, your old comments are displayed in comments column of main table. In case there are new data added, the comment field will return error or be empty in case you used IFERROR(...,"") in formula. You can add missing comments into 2nd (comments) table. You also can update existing comments in comments table whenever you need this. All changes will be displayed in main table.