Most interesting hook,

• CategoryViewer::generateLink - Doesn't allow us to change the title of a category, but since we can substitute our own link instead of the results of Linker::link, it would allow HTML changes to the rendering of the category. *Update*: this is only used in category pages.

These might help us with any changes needed in the category page itself:

• CategoryPageView - allows extensions to modify the CategoryPage instance before display.
• CategoryViewer::doCategoryQuery - allows us to change database query results used to display the list of categories on a category page.

Another nice hook,

• OutputPageMakeCategoryLinks - override default category link generation. Nice that it lets us do a batch calculation for the categories on a given page. Links include all HTML to render a category, so we are free to change the title.

OutputPageMakeCategoryLinks is the only remaining hook that might work for us, but still looking good. It has access to all categories, which in German includes the Frau / Herr category, satisfying our second criteria here.

The only extension to mess with OutputPageMakeCategoryLinks so far is CategoryTree, and it will only do so when $wgCategoryTreeHijackPageCategories is true, which is not configured on any Wikimedia sites.