what if i told you that you can skip flat files but still bulk edit bullets from a spreadsheet (e.g., google sheet)
there are so called writebacks available in g sheet, allowing you push changes to seller central directly from g sheet workbook.
how it works, u get a up to date list of your SKUs pulled from your seller central. along the skus needed attributes are pulled as well (adult flag, bullets, price etc).
you edit what's need; it could be 1-2 SKUs it could be 1000 skus.next before pushing edits to seller central you look at the before and after view to verify that everything looks okay (screenshot attached).
then click submit and your amz listings are updated.

simply wow