[duskwuff]

MediaWiki syntax is incredibly grody ('''bold''' / ''italic'', tables, template logic, etc), and has exactly one implementation in common usage (MediaWiki itself -- written in PHP, and horribly convoluted), and has no formal specification. The diff feature you're referencing as a "syntax-highlighted diff" is a simple diff of the source -- it's entirely ignorant of formatting, and the XML export is similarly just an export of the raw source.

Nobody likes MediaWiki syntax, not even its own users. It's awful. The only reason it's still used at Wikipedia is because there's too much content to reasonably convert.