Nice. I cannot close this ticket because of a Javascript error in the reply form. So i will just post my answer here. You may close this ticket after you read it.
Unfortunately, WPML does not support native WP features such as a different archive slug than the post type slug.
This is really an issue since many would want "/books" for the archive page, and "/book/harry-potter/" for the single post. With WPML you have to choose, because it relies on the rewrite=>["slug" => __('book')] value.
I hope this will be fixed, since it is a native WP feature.
If i use "has_archive" = __('books') without WPML, and switch the WP language, it will work as intended and and the archive will be named and translated correctly.
I understand that you want to define a separate slug for the archive and posts. At the moment, you can set a slug for custom post type via WPML Settings, which will apply to both archives and posts. As the capability to define separate slugs for archives and posts isn't present right now, I will bring this matter to the attention of our product team. Further steps will be taken based on the evaluation.
Please let me know if there is anything else you need help with. I will be happy to assist.
