Missing __() or _e() for translation

On line 1621, and 1832, and 1847, and 1867 you have:

echo "<p>Nice Try...</p>";

The above line, while untranslatable seems to be inside functions that duplicate existing WordPress access $capability checks and could therefore be removed altogether while moving the functionality to the fourth argument in add_submenu_page();

On line 1964 you have:

wp_die('Remote access disabled in wp-config!');

On line 1987 you have:

wp_die('Sorry, this access token has expired. Please ask the user to renew it.');

On line 1990 you have:

wp_die('Sorry, this is an invalid access token. You must ask the user to grant access.');