I am attaching a .xaml file and 2 xls to check the solution.
One xls has a table with some values.
Another xls is empty which will be filled with data copied from the first xls.
I have also added a column and written data to it like Pass, Fail using write cell.
One of the reason you did not see the newly added column was because you have not checked Add Headers. If you do so, your column is already being added and written to the excel. It was a simple mistake.
For writing data in the excel, there are many options, like Write Cell, Append etc. You can also tweak your logic to update the datatable first with the required Pass fail values and then directly write it.
Or you can put the Write Cell in a loop if you are performing other operations to find out whether it is a pass or a fail etc.
Hope this will solve the main problem of yours so that you can tweak the solution as per your needs.
Director - Technology, Nanite Solutionsappends.xlsx (7.9 KB)
res.xlsx (8.5 KB)
Sample_Excel.xaml (14.2 KB)