I think there is a name for people who want you to believe they are a lot smarter than they are. That's the impression I get from reading the entries where I know what it is, like the past perfect on page 287. Can you imagine any reputable source giving as an example of anything, "It had been being compiled by hand"? Wow. I also think there is too much copying, which is rampant in the grammar field, and there is certainly 'jamming', as in the example just cited. This is a book you should have on your bookshelf to maybe make people believe you're smarter than you really are. Nah. Why bother? Let it go.
Sorry, Oxford. I suppose this is the flip side of playing off your name, which you have done for centuries. Maybe it's time to catch up, which in this case means to start over and try harder to get it right. And, if you don't know, just say, "I don't know" and leave it until you find out, which may take a while if it had been being compiled by hand.