If Germany was a formable earlier then Germany. Sure, the ability to form Germany may be harder, but Germany was a kingdom in the middle ages before it became the HRE. Plus, when Charlemagne died, his realm was split into East Francia (Germany), Middle Francia (Lotharingia) and West Francia (France). France is an instant formable (You can form France if it doesn't exist), Lotharingia is a unique formable from only one set of missions (Sadly, just Burgundy and not any of the Lowlanders, Nevers or Rhinelanders) and Germany is only formable in adm 20.