pappkamerad is the german word for cardboard character (lit. “cardboard comrade” or “cardboard companion”)
after a little googling, i think the usages of the expressions have only little (if any) overlap, though. i guess the more suitable german analog to cardboard character would be “holzschnittartiger charakter” which in turn roughly translates back as a “character (sketched) like in a woodcut” which means it’s usually quite stereotypical and not very faceted.
berlin, moabit, 2016