Are there any large conservative Jewish communities in Germany?
Large communities would be a misnomer, but there are Jewish Communities in Germany. I lived in Germany for a year (1993), primarily in Bonn (then the capital) and there were many museums dedicated to “the past”. The capital city has since moved to Berlin, so it is possible the museums (and embassies) moved there as well. Check with the local Israeli Embassy (website or other) and they will direct you to where you want to go, whether it be a synagogue or group or museum. Bonn and Berlin would have the highest concentration and be tourist based.