Maybe...
Hi,
I remind... you can try this to get maybe the
"UTF-8 characters do no display" Problem out of the world.
In my Apache Conf File the was the line:
AddDefaultCharset ISO-8859-1
which makes big problems.
Because Tiki is set normaly to UTF-8, but with this line in the apache conf the browser switch automatically to ISO-8859-1.
Problem: all the special chars fucked up.
Try to comment out this line in your apache conf and afterwards create a wiki page with some special chars and then to create a pdf of this newly created wiki page.
If this line is not in your apache conf then forgett my post. 
;){kind=link}
;){kind=link}