VaultWiki doesn't add structured data to /threads/ pages, only to wiki pages. Neither auto-links nor general wiki links from BB-Codes include structured data. If Google is not complaining about structured data issues on wiki pages, we probably won't touch it.
The only structured data that I see on threads is defining post authors as Persons. However, it may not set all of the required properties about the person aside from the person's name; I would expect the URL to the relevant profile about that Person to be defined.
It appears that XenForo is breaking these Google guidelines:
Don't mark up irrelevant or misleading content, such as fake reviews or content unrelated to the focus of a page.
Put the structured data on the page that it describes, unless specified otherwise by the documentation.
Specify all required properties for your rich result type. Items that are missing required properties are not eligible for rich results.
By marking up only the Persons in a thread, the structured data appears irrelevant to the purpose of a thread. The Person data does not describe the thread; on its own, it is better suited to a profile page. To be relevant, each post should be scoped as a Comment, with the Person encapsulated as the post's author property, and the entire thread should be scoped as something like a WebPage, DigitalDocument, or a Conversation. This is a flaw in XenForo's usage of structured data.
Since VaultWiki uses XenForo's post template for its comments, you may receive the same violation on wiki pages that have comments. But once this is fixed by the XenForo devs it should automatically be fixed in wiki comments too. XenForo devs should perform a review of their usage of structured data to ensure that it is relevant, appropriately scoped, and conforms to Google's guidelines, or they should remove the structured data.
VaultWiki does a very thorough job at scoping its own structured data fully and appropriately so that it is relevant to the content. If you notice an issue on a particular wiki page, please let us know.
Marking this as a Forum Bug.