Each line needs a semicolon, fortunately I have done enough php to know that what you are doing is executing those settings as code and the missing semicolon made php fail(*).
Please don't worry, it is not executed as code. But it is not possible (or I don't know how to do it) to create an unlimited set of key value pairs in the DokuWiki config UI. So I decided to use a text field and parse it's contents. So I had to choose a format. I decided to choose
username="language";. You can have but don't need a linebreak between subsequent entries.
So both this examples should work:
Example A:
UserA="de";
UserB="fr";
Example B:
UserA="de";UserB="fr";
The bottom line is: it's no code that is executed, no security risk. The
; just serves as a separator.
P.S.: I am open for suggestions if someone has an idea for a better format. It just needs to be easily parseable via a regular expression.