When moving an existing multilanguage site (Jive CMS) to Drupal we need to redirect urls like /docs/DOC-1763 to the german version of a node. They are a lot, so we need a migration for it.

We're using the redirect module, but when setting the language to german it only works for /de/docs/DOC-1763, which is of course not what is needed.

How can we redirect old root urls like /docs/DOC-1763 to the new german version of this content? The url would be /de/something/different (node 5) for example.