KT17: I had not noticed the alphabetical sequence of the unclued lights and so initially had a different one at 13A. The eighth one (alphabetically) was Swiss, not German, so I am equally puzzled.
KT17, the German eighth refers to their eighth note on the scale, different to ours.
Helveticus, he was indeed Swiss, although born and died in France. But as above, the German dies not refer to him.