Fair enough, but then balance the game by making it easier to form the Reich, not the NGF. Period.
Also, chronologically speaking, Prussia defeated Austria which made it lose its leadership over the german states forever and then allowed the NGF. A prussian defeat would mean austrian hegemony and no NGF. So, IMO Austria AI has to be reworked so that it will focus influence in Saxony and therefore an early NGF goal will force an early war. If it´s impossible to change the AI then remove prussian investments in Saxony, or give Austria investment there. Therefore balancing the influence game. It might not be "historical" but how much stuff isn´t historical already?
Finally, the one GP alliance per country system is definitedly showing its limitation here. The result is simple: the side with France wins. NGF is buddy with ottomans or (gasp) Netherlands? It´s f***ed. Also it´s BS that a GP was allied with a GP all times. That´s a major game diplomacy flaw, right there. Before 1870 for all intents and purposes France had NO alliance. The current diplomacy model is totally artificial. And what´s worse - it doesn´t create historical outcomes 99% time.
Well, it's already insanely hard for AI to form Germany without human help. Actually, I've only once seen that happen, and still Germany got beaten up by France + Russia in the second war, where France wanted cores back ( Russia did not take part of the crisis where NGF got A-L ). If devs make it harder for AI to form NGF by diplomacy, it will never be formed, because AI Prussia can't win Austria in a war after 1950, when they finally get casus belli for hegemony wars. Actually it's usually Austria who uses that casus belli, if NGF is not formed before Austria gets it. Prussia just don't have enough manpower to win Austria. Also it's more than likely that they don't have all of their starting spherelings either, if it's takes longer to form NGF.
But no matter what, AI Prussia/NGF/Germany is still really weak, and still gets demolished by France and Russia, and any opportunist countries after those 2 destroy their military ( I'm looking at you Austria + allies ). Also they have really hard time making good alliances, since Austria will not ally them, and UK is next to useless. Italy can help them against Austria, but France + Russia vs NGF + Italy is still a lost case. At least in my games, Russia alone have double the military score of NGF. In human guidance Prussia is a waking giant, but so is any other starting GP, so I think this is working quite ok. If I could change things, I would rather have France and Russia ally only AFTER Germany is formed, not day 1.