Great trip report mate!
Being a German living in London, I go every year in December over to Germany (my Russian/ British wife insists
) solely to visit Christkindlmarkets.
Normally we travel to Berlin and visit also the market in Goslar which is extremely beautiful.
Hope you have enjoyed visiting my home country!
Nota bene: Sorry for your experience with Deutsche Bahn
- they are still better than the UK trains though