I am not sure anything is planned for immediate Vienna victory, will talk to the team.
Personally did play a lot with Bourbons in the GC and, by adopting a strategy equivalent to that used by Napoleon's opponents (i.e. never fight directly the big boss, attrition him), I succeeded. The key was to keep Marlborough and Eugene busy and harassing their LOCs...and shifting to Spain Vendome and Villars...it's easy to crush the Allies there with these two generals.
I also did a lot of raiding with my navy, landing troop parties in England and Ireland..they got defeated often, but wrecked havoc in the allies backyards...and the most fun with the Hungarian rebellion, it kept the best Austrian troops tied down there for months...
It's far from an hopeless cause