Hello and thank you for the review. :)
If I understand correctly, you want to add new engines and change their order in SSS but then have those same changes happen in the browser's engines. Is that it? If so, this is not possible. The browser engines work in a different way than SSS engines. They are completely separate things after importing them into SSS. As for the export function in SSS, it is only used for backing up your settings (you can also use Sync).
If I understood incorrectly please send me an email to firstname.lastname@example.org. The notifications for these reviews might not be the best. :)