Just for completeness in case someone else stumbles upon this thread, the documentation for templates and plugboards
says explicitly that plugboards change metadata in the book, not file names.
Plugboards affect the metadata written into the book when it is saved to disk or written to the device. Plugboards do not affect the metadata used by save to disk and send to device to create the file names. Instead, file names are constructed using the templates entered on the appropriate preferences window.