Sorry for the delay in coming back to you, Tilman. Here’s an updated keycommands_de.json file:
keycommands_de.json.zip (978 Bytes)
Before you replace this in your Dorico 5 application data folder, open it in a text editor if you want to change the shortcut assigned to the breathmark: I’ve used § for the time being (replacing your shortcut for the About Dorico window).