Anything to do with the content of the WIKI itself can be done by anyone and everyone. The wiki editor password is on the main FLP Wiki thread here.
By all means, if you're going to make something superior to what you're replacing, go right on ahead. I would definitely suggest though creating an alternate page to test your layouts and theories, and then edit the real pages at your leisure when you find that they work.
Also, keep in mind the Wiki content pages aren't necessarily for the use of HTML, and only use Wiki tags. Creating a sortable table, for instance, would require far more coding then necessary. Creating things that are so complicated for such a simple thing would, in my opinion, be a complete waste of time. However if you want to provide the code to integrate that sort of table into the wiki, be my guest! 