newformat in the german locale has the value “d/m/Y”, which I have absolutely never seen used in Germany. It should be “d.m.Y” instead which is really the standard way to write a date.

Also, ISO8601Long should be “Y-m-d H:i:s” and ISO8601Short should be “Y-m-d” like in the other locales because ISO is an international standard and doesn't change according to language.