Carol, you may be getting tripped up by regional differences here.
The suggestions and search engine hits are definitely not translations from the German, and I'm not translating either, because I never heard of this German expression before. On the other hand, I've used and heard the English expression for many years, it's very common, and there are tens of thousands of occurrences of it on the web.
The fact that average people find it quite an ordinary expression is borne out by the fact that you find over 100 occurrences of it by reviewers responding to books they'd read at Amazon; these are not at all examples of formal writing which might tend to have more high-falutin expressions, they are mostly just your average joe typing their comments about how they liked some book into a form at Amazon's site, so pretty informal use of language, and indicate they're well within the reach of many average speakers of English.
As a Brit, you're surely aware of the differences in American and British English, you are faced with this every time you go to the cinema ("movies" as we say ) to see a flick (a "film"). Well there are many, many other such examples, some you've heard of, and others you haven't. That doesn't make them wrong, it just makes them perhaps less useful for you, if no one in England uses them.
In the case of the "devil is in the details" you can find out how widespread the expression really is in the UK. Do an Advanced Search restricting results to the uk TLD (
http://www.google.com/search?btnG=Google+Sear...)--this gives 265 hits which shows that at least some Brits are aware of it. But for every UK hit there are nearly 90 hits on the web as a whole, so allowing for the fact that the US is 5 times as populous, one could say that the expression is 18 times more popular in the US than in the UK.
So, rather than think "translation from the German" think "import from across the pond".
