Hello @maybellyne
I’m not sure how to make this less abstract as an indexer tool is always a bit abstract but I’ll do my best.
Yoast SEO includes an indexer that basically caches information in the database to speed up it’s features.
See table PREFIX_yoast_indexable
This table contains information like the URL, ID, object type, sub type, parent, author, title, description etc.
The class instance for the breadcrumbs (and probably other features) uses this table to fetch it’s information for the breadcrumbs, link the URL and title.
This works great for most object types. Posts, Terms, etc. all work fine.
However, Post archives are a bit of a unique part of the WordPress ecosystem in that these are not editable by default for a user.
The page titles for these archives are made from the Post Type object labels used when registering the post type.
Now here is the issue/bug. Since a post type archive isn’t editable it seems the Yoast indexer also doesn’t query for the indexed data the same as it does with posts and terms.
When using a translation plugin like Polylang these post type archives are translatable, but the Yoast indexer doesn’t seem to take this into account when indexing.
Few indexed examples:
CPT 1 archive
permalink: domain.com/spanish-cpt-archive-url
breadcrumb_title: French Title
CPT 2 archive
permalink domain.fr/english-cpt-archive-url
breadcrumb_title: Spanish title
Basically, Yoast only indexes a single item for a CPT archive, not on a per-permalink basis. Translated permalinks aren’t indexed.
But… on the front-end it does load the incorrectly made indexed values!
So you would have (for example with The Events Calendar)
Home > Eventos > Event category > Event
Where in the example “Eventos” is the Spanish CPT archive title, not the English one.
Here it seems to set the indexed values: https://github.com/Yoast/wordpress-seo/blob/trunk/src/builders/indexable-post-type-archive-builder.php#L76
My first guess would be that the permalink_hash isn’t set correctly and this it doesn’t recognize that it’s a new page. Keep in mind though that while the slug might be the same, the domain (in this case) is always different so I would expect that the permalink_hash is also different.
Let me know if it’s more clear now!
Cheers, Jory