Earlier quoted context omitted.
Depends on the culture. Historically if you told a German 5:00, that meant 5:00 - nor 4:59, not 5:01. "Fashionably late" is an American thing.
Just curious if the German trait you mentioned you have witnessed first hand or hearsay?
Party timing is still something many of us struggle with as not every host does it the same. Some like the guests to arrive on time, others have adopted the more international habit of not expecting anybody during the first hour.