IMO the best way to edit reports is to edit the RML directly and bypass the libreoffice conversion. Iterable items become much easier to work with, like invoice lines on an invoice, because that process is a bit of a hack to properly set up in libreoffice.

Then, you don't need to do anything to the database. Every time the report is generated, the RML file will be re-read, making testing very quick. Just write in your changes on the RML file (which is just XML), save, and run the report again.