In all likelihood, you wouldn't have been able to call any of them in. Austria and Brandenburg are both friendly with the PLC, Hungary is Threatened. Austria and Hungary both have high enough relations that joining a war will cause them a stab hit. All of those modifiers were in game prior to Cossacks.
In the past, if you had been with them long enough or fought with them enough, high trust could have let you call Brandenburg and Hungary in. That's the only pre-Cossack modifier in your favour that you're missing, but you're below midpoint trust with Brandenburg, which indicates you wouldn't have had the trust in the past either. Now days the effect of trust caps out at +50 instead of +100, so that puts Hungary just out of reach with the available set of modifiers, since there's nothing to replace that last +10 you'd be missing from the Cossack change (+50 trust, +20 favours, +20 prepare).
Well, it makes sense until we start talking about a rather large blob. It would be interesting if nations could form some sort HRE-esque/anti-Napoleon defensive coalition against large neighbours, particularly aggressive ones.
The AI is meant to only ask you to a war that the AI would accept for favours or land as I recall. Whether it's working correctly, I'm not sure.
It is a ironman save (Sweden is not OP attempt), but i'll give the modifiers. I think the source of the problem is that even though commonwealth has been war mongering like crazy, they have been doing so eastwards and southwards keeping on good terms with the western neighbors, and now there is nobody left to challenge them that dislikes them. With the pre-cossack system i could have gotten them all into the war with no problem, so it is somewhat frustrating since it should be in the interest of all three to weaken their huge neighbor to the east.
