As pointed out in this comment currently the toolbar on a User talk page does not match the toolbar on the User page. The toolbar should be the same in both cases (including the contents of the overflow menu).
|user page||user talk page|
Changes needed to the toolbar on the User talk page:
- move Language icon into overflow menu
- add Contributions icon to Toolbar
- add User Groups and Logs to overflow menu
Code for the UserNamespaceOverflowBuilder is invoked when $userPageHelper->isUserPage() is true. It will also need to kick in for talk pages:
In theory nothing else should be needed but if any URLs are derived from the title this line here will need to call ->getSubjectPage( $title ) to convert a talk page title to a little: