If the Nazis meant "Reich" as "empire," they could have made that clear by translating it that way in English-language material they produced. They did not do so. They always used "Reich" in English translations. For one of many examples, see this page: http://www.calvin.edu/academic/cas/gpa/hitler1.htm. It is the official German government translation of a 1937 Hitler speech. Note that "Reich" is always "Reich." The Nazis did not consider Frederick the Great as having anything to do with the First Reich. They did view him as a great German. The problem is that your case depends on what appears to you to be "a very accurate translation." Wikipedia does not depend on what editors think, it depends on what they can support with reliable sources. You have yet to provide a single reliable source that supports your point. I and others have provided quite a few supporting the opposite.