The current directory from which you are executing the fwconsole command.
Unfortunately, on testing this I found that bi (without options) would only add new extensions, not edit existing ones. But when using the --replace option, the extension got completely replaced so you would need to specify all parameters.
Normally, that wouldn’t be an issue – you would export the extensions, edit the .csv with Excel and import the modified file. But you have no access to the GUI and I don’t know how you can do the export. Perhaps someone else can help with this.
See Unable to edit with BulkHandler on command line .
Otherwise, troubleshooting your lack of GUI access may be the best option.