Did some digging while waiting on other stuff to finish up…
It depends on the language you’re using. Each language will have a its own texts.php file in it. For example, English would be /ninja/resources/lang/en/texts.php, while German would be /ninja/resources/lang/de/texts.php.
What you’re looking for is the cookie_message variable. Should be around line 2872 or so, while “Learn more” will be the learn_more variable on line 53.
Just be aware that as soon as you do an update, any of those changes will revert back. Although technically, you could add some grep find & replace to the update script to make them permanent.