Valdemar II
Banned
I think downgrading Prussia is the key problem. You can get you're target with the historical Austria because, barring dramatic changes it will always be tied to its non-German lands which prevents it forming a likely German unifier. Also, possibly because of its multi-national structure, it seems to have been plagued far more by bureaucracy and inefficiency.
That was primary a problem which began to develop between 1814-1848, before that it was a state on the forefront of institutional developments. Honesty I blame the reactionary wave which hit Austria after the Napoleon Wars. Ironic a major part of the problem was wrong analyses of long term developments. If they had choose short term gain in 1815 rather than setting up the German Confederation, going after the rich North Italy and trying to set up the old status quo or a greater degree of economical integration of the German Confederation afterward Austria would have done much better.
The best thing they could have done in 1815 was to say fuck long term gain and try to so much of Germany as possible, split Saxony with Prussia, push as hard as possible for land from Bavaria and afterward they should have tried to push a unitarian state over their empire.