Unfortunatelly this module doesn't work with non-ASCII usernames. Also it can corrupt you SMF database (user willn't be able to login) if you try to change password from DokuWiki for user with non-ASCII characters in username.
So I think that Doku should not be able to modify SMF database at all, but should correctly support all other features.
I write more correct module for authorisation via SMF database which support:
* Unicode symbols in usernames (of course your SMF database must be in utf8 encoding).
* Allow to login by email (like in SMF)
* Full support of user's groups (including post groups). Also all SMF users in Doku are in 'defaultgroup' (you can change name of this group in Doku settings), so you can add ACL's for all users succesfully logged in.
You can get this module here:
Soon I'll add version for SMF 2.0.