User info page link does not exist when using plone.app.multilingual

I'm setting up a new site for SolydXK and I've setup the English and Dutch language with plone.app.multilingual. Everything functions very well except for the generated link to the user info page.

A news item contains a line with information of the author which contains a link to the user's info page:
nl/author/user_name
However, the link does not exists. This one does:
author/user_name

How can I setup a user info page in both languages and make sure the link to that page (nl/author/user_name) does exist?

I was able to fix this issue only for document views, but not for listings (or collections).

In my site policy package I added this in a overrides.zcml file:

  <browser:viewlet
      name="plone.belowcontenttitle.documentbyline"
      manager="plone.app.layout.viewlets.interfaces.IBelowContentTitle"
      class="plone.app.layout.viewlets.content.DocumentBylineViewlet"
      template="templates/document_byline.pt"
      permission="zope2.View"
      /> 

In the template, I replaced
/@@plone_portal_state/navigation_root_url
by
/@@plone_portal_state/portal_url

There's other packages with this issue, but overriding them all would be a pain.

I wonder why navigation_root_url is used instead of portal_url ...

Thanks Marc, I'll definitely take a look at it.