HTML's has a number of attributes for expressing language and how one URL relates to another. Unfortunately, JSON-LD has no such mechanism, so data in a feed cannot express things like "the endpoint is in Japanese" or "the endpoint is an alternate link".

We have touched on this idea in issue #561. A clearer, more extensible mechanism would be to add LinkRole:

A LinkRole is a Role that represents a Web link e.g. as expressed via the 'url' property. Its linkRelationship property can indicate URL-based and plain textual link types e.g. those in IANA
link registry or others such as 'amphtml'. This structure provides a placeholder where details from HTML's element can be represented outside of HTML, e.g. in JSON-LD feeds.

Itt would have two properties:

inLanguage: The language of the resource. (This property already exists. We would be extending the domain.)

linkRelationship: Indicates the relationship type of a Web link.