You can freely modify headers, that's why I'm giving users the option to do so with the drop-down menus.
I'm not sure what you're trying to do, why are you using an identical value for both Unknown and Unique ID? They're separate, the Unknown ID comes from the original template, the Unique ID should be your private ID dumped from an original cartridge (unless you're making a template for an offline game, in which case you can put in random gibberish or Zero-Fill).
when you say original cartridge, you mean from mh4u specifically or will any private ID suffice? and how do i get it, been searching everywhere but no luck atm