The wpml_set_element_language_details action element_type need to be with the correct prefix that WPML use:
From the WPML Docs
element_type(string) The type of an element. Can be a post type: post_post, post_page, post_attachment, post_nav_menu_item, post_{custom post key} or taxonomy: tax_category, tax_post_tag, tax_nav_menu, tax_{custom taxonomy key}. Defaults to post_post if not set.
In your case it should be post_projects but you can also use wpml_element_type to get the correct prefix like this:
$element_type = apply_filters('wpml_element_type', 'projects');
Resources:
https://wpml.org/wpml-hook/wpml_set_element_language_details/