Okay I'm giving up for now. Sieg für die Volksfront and Sieg für die Einheitsfront seem impossible.
Viewing post in Social Democracy: An Alternate History comments
This shouldn’t be happening all the time; the achievements should be possible. It’s possible that you’re taking too many actions that increase the coup progress, like economic nationalizations or reducing military funding. You should be able to avoid the March on Berlin by successfully banning the SA and Stahlhelm.
Braun’s ability is intended to be strictly better than Müller’s.