I am using JS Animated Contact Form with this line of validation regex:
rx:{\".name\":{rx:/^[a-zA-Z\'][a-zA-Z-\' ]+[a-zA-Z\']?$/,target:\'input\'}, other fie
You should use in your regex unicode codes for characters, like \u0080. For German language, I found following table:
\u0080
Zeichen Unicode ------------------------------ Ä, ä \u00c4, \u00e4 Ö, ö \u00d6, \u00f6 Ü, ü \u00dc, \u00fc ß \u00df
(source http://javawiki.sowas.com/doku.php?id=java:unicode)