The website of the professional association for Chinese (Fachverband Chinesisch e.V.) contains information on initial and in-service training.
https://www.fachverband-chinesisch.de/chinesisch-als-fremdsprache/lehrerausbildung/

The Confucius Institute at the University of Heidelberg regularly offers an examination for the "International Certificate for Teachers of Chinese".
https://konfuzius-institut-heidelberg.de/sprachbereich/pruefungen/internationales-zertifikat-fuer-chinesischlehrer/

You can also find information on initial and further training courses at
China-Schul-Akademie
https://www.china-schul-akademie.de/fortbildungen/

and the website of the French Association of Teachers of Chinese
https://www.afpc.asso.fr/