You cannot do this. You are attempting to order “Post Type A” by a values associated with “Post Type B”. In order to order “Post Type A” by these values they need to be saved as custom fields for “Post Type A”.
This is possible, but to do it you need to create an acf/save_post filter. In this filter you would get the values from the related post and save them as custom field values for the artwork post type.
