Hans Peter Richter wrote multiple young adult historical fiction books about the rise of Hitler, which have been translated to English and are very approachable

Hans Peter Richter wrote multiple young adult historical fiction books about the rise of Hitler, which have been translated to English and are very approachable. His most famous is Friedrich. They were written in the 80s, which isn't exactly modern but is certainly more recent than Herman Hesse. Not recent at all, but as you mentioned Goethe, the comparatively lower class playwright Friedrich Schiller was considered to be his intellectual equal and rival.