This is just to make some suggestions about this. Should stress I am quite content that an effective suicide dow by the Austrian AI is NOT hardwired into the chain. From our perspective, the events of 1859 may seem 'logical' but there is a good reason why Italian history books talk about the 'miracle of 1859'.
However, as it is the chain seems to peter out with the mobilisation event. There is no reason for the Austrian (either player or AI) to do anything. The revolt risk is a pain, but can be kept under control. There is no threat of escalation elsewhere in the empire, so its quite logical to accept some low level nuisance in Lombardy and carry on as before.
I'm not sure how to model this but at the moment few players are reporting an 1859 style unification so the chain isn't really working (all it does is to protect S-P via the French alliance). So what about one of two final steps.
First if the Austrians don't respond aggressively, then some degree of unrest elsewhere in the Empire. That might make it worthwhile to risk a war if the alternative is more generalised unrest?
Second, end the chain (post mobilisation) with a forced diplomatic crisis. That would allow the player(s) to seek to be as aggressive or passive as they wished but at least would put up a large prestige pot. So if S-P plays aggressive (most likely) they either get the war they wanted or a large prestige boost for showing the world they can (diplomatically at least) force the Austrians to back down.
Either iteration at least creates uncertainty and a larger cost to just ignoring the rise in revolt in N Italy?