A solution to the Semantic Mediawiki (SMW) problem been found and SMW has been reenabled. SMW is currently rebuilding properties on various pages, until that is done expect to see further "not found" issues or incomplete item lists. Work on porting SMW templates to Cargo continues on as well, potentially causing temporary disruption to pages.
Tags are internally used by the game to describe certain properties/aspects of entities. Those are then usually used later to govern certain rules about those entities, such as which modifiers can spawn which items.
Most entities, like monsters, areas, mods and items come with their own list of tags. The tags are used to describe some properties of those entities, for example currency items are usually tagged with