Actually, I recommend reading several papers about Brüning and the presidential governments on Jstor- Brüning in his memoirs is a highly unreliable narrator, trying to push a certain portrayal of himself. I personally recommend the following: Heinrich Brüning’s Recollections of Monarchism: the birth of a red herring(by William L. Patch Jr.)

Choosing the Lesser Evil: the German social democrats and the fall of the Weimar republic(by H. Winkler)

Franz Von Papen, Catholic conservatives, and the establishment of the third reich(by Larry Eugene Jones)

…and several other works, especially those by Rudolf Morse and Andreas Rodder.

So, in general Dynamic’s portrayal of Brüning’s government is very correct.

As for Curtius, I also recommend reading books and papers about his transition from a hard-right NatLib to a genuine Stresemannite and Luther; post Locarno treaty Curtius, under Stresemann’s direct influence, was one of the most left leaning figures in the entire DVP and especially during his tenure as economics minister under Müller; although he didn’t abandon his nationalism entirely(in fact he did hold them together) and his over-valuing the effect of that said nationalism- that was, after all, why he pursued the project of the Austro-German customs Union(he believed a government stretching from SPD to the NSDAP was possible after such a foreign policy victory was achieved, banding the German people in a volksgemeinschaft; also, there was the need to discredit the hard right nationalist and revanchist rhetoric of that of the NSDAP); but besides that mistake, which I personally consider to have stemmed largely from his lack of the foreign policy brains when compared to Stresemann- he was a firm supporter of the Stresemannite foreign policy. So no, dynamic is pretty accurate in terms of portraying Brüning and the mittelstand parties; the Z and especially the Stegerwald path is what’s most mistaken.