I have gone through the .po file with Poedit for my language (NL) but I cannot find the entries with the text for the signup page.
http://mydomain.tld/wp-signup.php (Link edited so not to point at a squatter site ~ drmike)
For example: it still displays: (Must be at least 4 characters, letters and numbers only.) at the username field.
Can anyone tell me where I might edit this?