Answer
Rather than trying to configure IFS Connect Routing Rules/Addresses to dynamically pass a per-record recipient address for this, it's more straightforward to implement directly in PL/SQL using the Command_SYS package, from within a Custom Event triggered when the file is stored in EDM: use EDM_FILE_API methods to check whether a converted rendition of the file exists (falling back to the original file type if not) and resolve the actual local file path for that document, then use the PL/SQL Access Provider record API to read the file's content from the database into that local file, and finally call Command_SYS.Mail, passing the resolved local file path as the attachment parameter and setting the To/From addresses dynamically from whatever source values your logic needs, rather than trying to achieve the same dynamic-recipient, file-attached email purely through IFS Connect routing configuration.