In the question How did the Allies deliver the Moscow Declaration to the Nazis? the answers seem to focus on just one side of the communication, namely how the allies broadcast their message of the Moscow declarations. The general answer to that is that such a declaration was printed in newspapers, sent over radio and shown in newsreels, primarily.
To quote from Michael J. Bazyler & Frank M. Tuerkheimer: "Forgotten trials of the Holocaust", New York University Press: New York, 2014:
On November 1, 1943, the foreign ministers of the U.S., U.K., and U.S.S.R. issued the so-called Moscow Declaration, putting on notice Germans participating in “atrocities, massacres and executions” that they would be tried for their “abominable deeds” in the countries where they committed these deeds.
However, that does not explain the other side of the communication: when and how where Germans aware of the content of these declarations?
The demand for an unconditional surrender was picked up soon, but the part on atrocities seems to be wholly forgotten.
Looking through Wikipedia we find uncited conjectures on English, French and Russian pages about Mass suicides in 1945 Nazi_Germany. There, one of the reasons for the suicides is stated as:
Finally, others killed themselves because they knew what would happen to them following defeat. The Soviets, Americans and the British had made it clear in 1943, with the Moscow Declaration, that all those considered war criminals would face judgment.
But these are conjectures that are absent on the Portuguese and Hebrew version of Wikipedia. (Not to mention that the German Wikipedia page for that seems to be missing). The English Wikipedia page gives as its main source the book Christian Goeschel: "Suicide in Nazi Germany", 2006 in which the Moscow Declarations are never mentioned.
If one searches the German speaking web it seems that the Moscow Declarations are only relevant for the history of Austria.
Rarely are any scholarly titles speaking about those declarations really concerned with Germany, only mentioning them en passant when introducing the war criminal trials at Nuremberg.
And what all those I found leave out is when and how the Germans at different levels of society or Nazi structures became aware of the declarations, or whether at all. The timeframe 43–45 for the Germans' perspective is usually overlooked. Completely?
Foreign newspapers or newsreels were largely unavailable to the masses. Listening to foreign radio was possible but forbidden and violators prosecuted. Talking about it was forbidden as well and prosecuted as defeatism. News transmitted directly from the front where soldiers might have learned about it is another possibility. That Goebbels would allow the widespread dissemination of the exact words seems very unlikely, but quite possible for extracts twisted to suit the regime.
But that is speculation. Reasons for being in angst at the end are many. The Goebbels perspective for the trial is a given. But the rest is circumstantial reasoning. General fear of Russians, bad conscience after all, etc come to mind.
When did the Germans learn about the declarations, especially the "Declaration on Atrocities"? That includes a more detailed explanation of the different levels, from NSDAP and Wehrmacht leadership, ordinary party members or civilians.
One en passant mentioning, just focusing on the content, not the transmission or reception or reactions at the time:
Die Deklaration hatte Prozesse für die Zeit nach einem Waffenstillstand angekündigt. Vgl. die Erklärung über Grausamkeiten auf der Drei-Mächte-Konferenz in Moskau vom 30. 10. 1943, in: Gerd R. Ueberschär, Ausgewählte Dokumente und Übersichten zu den alliierten Nachkriegspro- zessen, in: Ders. (Hrsg.), Der Nationalsozialismus vor Gericht, S. 277–301, hier S. 285–288. (quoted from: Andreas Hilger: "Sowjetische Justiz und Kriegsverbrechen. Dokumente zu den Verurteilungen deutscher Kriegsgefangener, 1941–1949", VfZ 3/2006. PDF)
Who was made/became aware of what details from the "Declaration on Atrocities" at what level and at what time and what were the reactions to that?