How to use register_sidebar’s ‘before_widget’ unique id generator into its other parameters like ‘before_title’?

by

You could use the dynamic_sidebar_params filter to do your own substitution.

Something like this:

add_filter('dynamic_sidebar_params', function($params){
    $params[0]['after_title'] = str_replace( '%1$s', $params[0]['widget_id'], $params[0]['after_title'] );
    return $params;
});