Sort search results by custom field

Hi there,

Firstly, thanks so much for creating and maintaining a fantastic plugin! It’s easy to use and works great.

My question is, I am wondering if it is possible to sort the results of the plugins’ search, specifically a custom field?

For example I have a a custom post type ‘publications’ and am sorting the archive page using this:

function sort_publication_date_field( $query ) {
	// do not modify queries in the admin
	if( is_admin() ) {
		return;		
	}
		if( isset($query->query_vars['post_type']) && $query->query_vars['post_type'] == 'publications' ) {

		
		$query->set('orderby', 'meta_value');	
		$query->set('meta_key', 'publication_year');	 
		$query->set('order', 'DESC'); 
	}
	
	return $query;
}

add_action('pre_get_posts', 'sort_publication_date_field');

But when I use the search provided by the wp-custom-fields-search plugin, this function does not seem to be called, I expect because it is not using the main search query (?).

So, what I am wanting is to sort/order the search results by their publication_year.

Is there some hook I can use to intercept the wp-custom-fields-search query, or setting I am not seeing in the UI to apply this function?

Thank you in advance.