The lists "Unused images" and "Missing commons category links" suggest files and category links which should be added to monument lists.
Any tool should be appended to semi-automatized (assisted) update of the monument list. There exists an excellent script AddCommonsCatLinks by Dudemanfellabra which can be inspirational and utilizable for it.
- add images and commonscat links (based on ID template, based on "Unused images" and "Missing commons category links" lists) (tool actually bypasses the lists and searches the category on commons instead)
- detect (and optionally remove or correct) links to non-existing pages (already implemented)
- detect and correct links to hard and soft redirects