Change the label / add a new class / redirect for login/register buttons

add_filter( 'wpj_header_button_filter', 'wpj_custom_login_register_buttons' );

function wpj_custom_login_register_buttons( $buttons_list ) {
global $site_url_localized;
// Changes to reflect on all pages 
$buttons_list['login']['label'] = __( 'New name for login', 'wpjobster' );
$buttons_list['register']['label'] = __( 'New name for register', 'wpjobster' );
// If some classes which contain some CSS need to be attached to the button
$buttons_list['login']['a_class'] = '';
// if you want to redirect the user to other website or page  
$buttons_list['login']['url'] = '';

 // Only for register page
if ( $GLOBALS['pagenow'] === 'wp-login.php' && ! empty( $_REQUEST['action'] ) && $_REQUEST['action'] === 'register' ) {
$buttons_list['login']['label'] = __( 'New name for login', 'wpjobster' );

$buttons_list['register']['label'] = __( 'New name for register', 'wpjobster' );



// Only for login page
if ( $GLOBALS['pagenow'] === 'wp-login.php' && ( ! isset( $_REQUEST['action'] ) || $_REQUEST['action'] != 'register' ) ) {
$buttons_list['login']['label'] = __( 'New name for login', 'wpjobster' );
$buttons_list['register']['label'] = __( 'New name for register', 'wpjobster' );
}

// Both login and register pages
if ( $GLOBALS['pagenow'] === 'wp-login.php' ) {
$buttons_list['login']['label'] = __( 'New name for login', 'wpjobster' );
$buttons_list['register']['label'] = __( 'New name for register', 'wpjobster' );
}
return $buttons_list;
}