Despite the website showing a warning, the kit is actually available again (after over 1/2years wait) at: https://www.catanshop.de/zubehoer/zubehoer/9104/catan-zubehoer-kompatibilitaets-kit-fuer-die-siedler-von-catan
Despite the website showing a warning, the kit is actually available again (after over 1/2years wait) at: https://www.catanshop.de/zubehoer/zubehoer/9104/catan-zubehoer-kompatibilitaets-kit-fuer-die-siedler-von-catan