Using umlauts ("ä", "ö", "ü") for FULLNAME will not name user as defined.

[andredb90]

For example: -f "John Snäjder" will show as John SÃ1/4^jder.

[geoff-nixon]

That's interesting. is it actually shown as "SÃ1/4^jder"(with the characters '1','/', and '4' decomposed into three ASCII characters? Or is it "SÃ1¼^jder", with the single character/code point "¼" (U+00BC)? If the latter, then the issue is that the remaining vestiges of Open Directory are still implementing the pre-LDAPv3 use of ISO-8859-[X] Code Pages, rather than fully implementing UTF-8. Are you using that character using a German[ic] keyboard that is generating precomposed characters? Have you tried entering them decomposed, i.e., pressing the "option-u" key combination, then the letter 'a'?