I presume it's because Germany uses the comma as a decimal separator instead of a dot.

I eventually settled on just exporting Excel because I couldn't get both the encoding and separator to work at the same time.

Another fun story is that a coworker lost data, when they opened a csv, wrote data to a second sheet, and then saved it. A sane program would probably have brought up a save-as window. Excel didn't. It just discarded the second sheet.