That's the problem, and the index seems to be building. For stuff that is indexed, the results seem refreshing.
Since the poster says he doesn't understand what they are doing, I'll try to explain the idea of indexing. This is in general terms, and someone may have a better explanation than me.
First of all, searching or sorting data is about the slowest thing a computer can do. There's all sorts of theory on how to build the fastest search algo. What Google does, is not build a search algo, but an index. So, the searching isn't done in real time, but some time before you search for a term.
For every term someone would search for, the results have to be predetermined. If they, or Google, tried to determine the results at runtime, it could take hours to return one query. So, every page it spiders, it archives. It then determines the relevant terms. Then, when an index is being built for that term, it will generate a list of maybe the top 10,000 articles related to that term. Then, when you search for it, you get that list in order, which is very fast and easy to return.
So, you search on this engine, and the results for every word in the dictionary do not yet exist.
I'm not sure how clear that is, but I've done similar things before, and it takes lots of space to hold the index. It also takes a lot of time. I understand, that in the early days, it would take Google a month to rebuild their entire index. Currently, Google is updating their index on a continuing basis.
So, they have articles related to COBOL, but no index for it. That, or it's a joke, because the use of COBOL cripples the mind; its teaching should, therefore, be regarded as a criminal offense.