The alternate link to the page itself is missing.
A language definition is specified wrong in alternate links.
A language definition is specified wrong in alternate links.
A language definition is specified wrong in alternate links.
A language definition is specified wrong in alternate links.
A language definition is specified wrong in alternate links.
A language definition is specified wrong in alternate links.
A language definition is specified wrong in alternate links.
A language definition is specified wrong in alternate links.
A language definition is specified wrong in alternate links.
A language definition is specified wrong in alternate links.
A language definition is specified wrong in alternate links.
A language definition is specified wrong in alternate links.
A language definition is specified wrong in alternate links.
A language definition is specified wrong in alternate links.
The href language is specified more than once in alternate links.
(Nice to have)