See the new syntax file here. It fixes both of the problems reported below.
I'm teaching myself how to write syntax files for vim by fixing several issues (and up to certain extent, taking over the maintenance) of the vim syntax (highlighting) file for ikiwiki.
I'd like you to document here which problems you have found, so I can hunt them and see if I can fix them.
Arguments of directives with a value of length 1 cause the following text to be highlighted incorrectly. Example:
[[!directive param1="val1" param2="1"]] more text ...
A named wikilink in a line, followed by text, and then another wikilink, makes the text in between the links to be incorrectly highlighted. Example:
[[a link|alink]] text that appears incorrectly .... [[link]]