score:6
You are not alone in being frustrated by the lack of sources in Brugsch's text. As far back as 1893, in a paper titled La Mythologie Egyptienne, in his book, Études de mythologie et d'archéologie égyptiennes (in French), the famous Egyptologist, Gaston Maspero, also lamented the fact that Brugsch chose not to identify his sources individually!
As for Brugsch himself, on page 746 of Religion und mythologie der alten Aegypter he seems to claim that the quotes are taken from ägyptische zeitschrift, which I'd assume refers to Zeitschrift für Ägyptische Sprache und Altertumskunde, one of the oldest - if not the oldest - Egyptology journals.
The first 59 volumes of Zeitschrift für Ägyptische Sprache und Altertumskunde, covering the period from 1863-1924, are available online at the Internet Archive. Since Brugsch's book was published in 1891, this covers the period we are interested in.
Now, German isn't my first language (I would by no means consider myself to be fluent in the language!) but I've checked every article by Brugsch from 1863 to 1895 and wasn't able to locate the quotes used in his book. I'd guess that I am following in the footsteps of Maspero in that regard.
All I can do at this stage is to echo Maspero in his lamentation that Brugsch chose not to identify his sources individually!