Keep in mind that this is scientific community, so most of the (official) communication is anyway in English, and from my personal experience people don't have

Keep in mind that this is scientific community, so most of the (official) communication is anyway in English, and from my personal experience people don't have a problem switching to English anyway. There is also an International Office (https://guest-services.desy.de/international_office/index_eng.html https://guest-services.desy.de/international_office/index_en...) providing help when dealing with government and city administration.