But it looks like it is mostly for the UK. Do they work for Germany, too? Do i get wrong interpretations from SquawkBox if i use it in Germany?
In many cases yes. But in many cases no. UK Domestics are used in Germany for German Domestics. Police in Germany shall use same code ranges as in UK, but of course the stations in the List do not match. Same shall count for the military section. But you can back-up and amend the squawk_codes.txt in SQUAWK BOX folder to set the correct parameters.