Is there a way to set the default font for text created with Write>Create System Text?
Other than changing the Default Text paragraph style? No, I don’t think so. But you could define a new paragraph style for system texts and easily choose that one from the dropdown list in the text editing panel.
But I’d have to do that for every text object I created then, I suppose? Dorico really has a long way to go with text styles, ugh…
Why don’t you just change the Paragraph Style for Default Text if that’s what you normally want?