I highly doubt the average Excel user with no programming language background whatsoever will be able to reproduce this query or understand what it does.
Then it can just be added into the BIP and that's it. It could even be exported with the data as a comment at the end of the file.
There aren't standard for comment on CSV file though. The comment would create new row where it's second column is empty.
A third column would instead increase the file size by 50% as you'll add a 3rd field for each dataset.
It should be less than 50% since length of address/txid is longer than text "transaction" or "address".