When you want to know if all the articles on a specific subject have been written, you need something that actually helps. Wikidata helps because it knows about subjects and knows if there is an article in a language.
The Lua code shown below is "trivially easy" to create ... when you know Wikidata and Lua. For me it is a life saver; it allows me to build a list and use it on any Wikipedia.
It shows the Wikidata label used in the local language and, it shows if there is an article in the local Wikipedia. Really powerful stuff if you need this functionality.
The next challenge is to create the Lua module on every Wikipedia..