Below is an example where you can change the standard text output from Frontier Post, if a user does not have any post created:

Add the below to functions.php:

function fp_change_text_strings( $translated_text, $text, $domain ) {
	
   // Limit to Frontier Post for performance reasons
  if ($domain == "frontier-post")
     {
     switch ( $translated_text ) 
        {
        case 'Sorry, you do not have any posts (yet)' :
        $translated_text = "No Posts";
        break;
        }
     }
     return $translated_text;
}
add_filter( 'gettext', 'fp_change_text_strings', 20, 3 );