Hi,
no you are misunderstanding something, it's not possible that such parameter of sh404sef changes the format of your website's URLs. Unless you changed something else outside what is written in the PDF document.
However if for some weird reason you want to use an alternative solution, you have specify the format parameter for all other sitemap links accordingly.
https://www.ifootpath.com/sitemap/mobile?lang=en&format=mobile https://www.ifootpath.com/sitemap/images?lang=en&format=images
... etc ...
Best regards
