Changing the language of a permalink should redirect to the same permalink in that language

Steps to reproduce:

Visit a permalink page on the support portal, say https://support.torproject.org/id/faq/faq-2/. Then change the language from the menu on the top right to a different language, Catalan in this example.

Actual Result:

The support portal redirects to the main page for Catalan.

Expected Result:

The support portal should redirect to the same question and not to the main page. So in this case, it should redirect to https://support.torproject.org/ca/faq/faq-2/ and not https://support.torproject.org/ca/.