String.split("Freude schöner Götterfunken") would be preferred since it will use the Unicode word break algorithm which is much more flexible than breaking on an ASCII space character.

iex> String.split("Freude schöner Götterfunken") 
["Freude", "schöner", "Götterfunken"]

From the docs:

Divides a string into substrings at each Unicode whitespace occurrence with leading and trailing whitespace ignored. Groups of whitespace are treated as a single occurrence. Divisions do not occur on non-breaking whitespace.

This works for me:

iex(1)> String.split("Freude schöner Götterfunken", ~r/[^[:alnum:]-]/u, trim: true)
["Freude", "schöner", "Götterfunken"]

Is your shell not in UTF8 perhaps?