[Waiting for user confirmation] WPML and Custom Slug Translation for a Custom Permalinks Plugin

Background of the issue:
I am trying to use a custom plugin (Slicked Custom Permalinks) to modify the permalink structure for several custom post types (lineups, set-times, guides) that are linked to a parent post type (festivals) via JetEngine relationships. The plugin is configured to dynamically include the parent festival’s slug in the child post URLs. The desired URL structure is /translated-festivals-slug/parent-festival-slug/child-post-slug/. The plugin uses WPML to translate the base slug (festivals) into each language dynamically using wpml_register_single_string and wpml_translate_single_string. Here’s a summary of what the plugin does: Registers a Base Slug for Translation: do_action('wpml_register_single_string', 'Custom Permalinks', 'base_slug', 'festivals'); $base_slug = apply_filters('wpml_translate_single_string', 'festivals', 'Custom Permalinks', 'base_slug'); Adds Rewrite Rules: Registers rewrite rules for the translated base slug: add_rewrite_rule('^' . $base_slug . '/([^/]+)/([^/]+)/?$', 'index.php?festival=$matches[1]&name=$matches[2]', 'top'); Query Variable Handling: Adds festival as a query variable and modifies the main query to include the custom post types (lineups, set-times, guides). URL Construction: Modifies permalinks dynamically to include the translated base slug and parent festival slug: return home_url('/' . $base_slug . '/' . $parent_festival->post_name . '/' . $post->post_name . '/'); Link to a page where the issue can be seen: hidden link

Symptoms:
The translation of the base slug (festivals -> festivaluri) works correctly, and the URLs appear as expected in all languages. However, visiting the translated URLs results in a 404 Not Found error, suggesting a possible mismatch between the rewrite rules or WPML’s handling of the translated slug.

Questions:
Does WPML fully integrate with dynamically registered rewrite rules for translated slugs?
Is there a better way to register and handle the translation of the base slug to avoid 404 errors?
Are there additional steps required to ensure compatibility between WPML and JetEngine’s relationships when generating and resolving custom permalinks?