Master Jan Silberstorff collaborated with Grandmaster Chen Xiaowang on a translation of the latter’s book The Five Levels of Taijijuan.
I believe Master Silberstorff is currently teaching in Hamburg Germany, but it is likely a good idea to contact the World Chen Taiji Association of Germany. I’d be just thrilled if most of our students got to near the top of level 1 (so a level 1.8 I suppose). My current understanding is that once a student gets to level 3 he or she has to make most further progress on his or her own. That would seem to mean that the challenge is how to teach so that students move through level 2 and are motivated or aware of what further progress entails.