Yet, this page is rendered: /de/contact/kontakt/index.html (wanted: /de/kontakt/index.html).
page = "/:slug/"
does not change the URL.
Background:
I would like to avoid translationKey. This can get tricky.
It would be great to have all related content in one folder—including page resources. Therefore I am trying to avoid e. g. contact.md and contact.de.md in the root folder.
It also allows (simulating) deep nesting/subfolders of leaf pages—a feature I always missed(*). The only disadvantage maybe is that you need to slugify all leaf pages.
Yes, I had tried contact = "/:slug/", but it did not work—and the site is far too big for this.
(*) My hack for deep nesting was using _index.md files in subfolders with front matter layout = "single". Your hack is a lot more out of the box!