https://tiddlywiki.com provides a Download Empty Button and lets you to download a clean copy of vanilla TiddlyWiki. It uses a saveTiddlerFilter as below: (see $:/editions/tw5.com/download-empty)
If discourse-tags find an exact match in the title of the thread, the tag will be not shown, since the search dialogue will find that word anyway in the title.
The number of tags is limited to 5, so if a tag does not show up, you can add an other one if it fits.
I would assume the +[sort[title]] was just to guarantee the list of tiddlers to include were sorted by title, since system tiddlers are organised in a standard order, and read nicly that way
It is done so that the tiddlers within a TiddlyWiki file always have a consistent ordering, which makes it easier to track changes with Git and other source code management tools.