Currently the search engine of Wikidata indexes all strings in labels, descriptions and aliases, but not in statements. Take for example https://www.wikidata.org/wiki/Q219831 / https://www.wikidata.org/w/index.php?title=Q219831&action=cirrusdump . So searching for "SK-C-5" (the inventory number) or "177124540" (the viaf id) won't return the item.
As a user I want to be able to search for a string that is somewhere on the item and find the item.
This task is about putting it somewhere in the output. Probably just append all the strings to the text output and ignore the language (like is done right now for the labels/descriptions/aliases) and improve on it later.