Okay there are few things. First technically wardens and nobles are not in charge Solonias church and duke are these is whole point why they are doing there coup. so blaming all of it on them is not right. duke and church and rossarias army's ARE different faction from nobles. its mainly dukes fault i hope i don't have to explain why.
Second twins are kind of looked like jokes in these community but they are very far from it. they have fucking teleportation in medieval times these is such a big advantage its unimageable. Warden and everyone is operating without these knowledge or even that demon lords are back(they don't believe rowan because lol teleportation dose not exits ) what twins and rowan mange to achieve for astarte battle is frankly amazing and i can guarantee almost no medieval nation would be able to stop them in that scenario. so why yes warden could have done better ods where not on hes side.
third When you start wardens route rowan is no longer hero He is villain by every measure. he has blood of tens thousands on hes hands. Even rastadel is beyond saving when rowan talks to warden by every law in the world Rowan deserves to be hanged for hes crimes against humanity. Rowan had a choice of hes life or innocent people and he chose hes and condemned thousand to death or worse.
fourth you can say what you whant about Warden that he is classist and has stick up hes ass BUT he is still best military commander rosaria has left and only person who can realistically lead resistance against twins Plus he is incorruptible.
fives we are in medieval world and Wardens knights and nobles are best fighting force rossaria has left. They are only real force that has any power to oppose twins army's in rossaria. they have troops, connections and skill to lead resistance against twins and every motivation to do so and they will most likely do it in next game
in conclusion warden route is only route where any real resistance to twins is possible and is route that definitely deals twins most damage.
Also rowan deserves every time hes teeth get kicked in because LoL telling warden what's about to happen after HE fuking destroys all the capitals defences and brings twins army to door IS not action of good man. Rowan thinks that he can both Survive and bring twins down without cost and lol thats not happening.
Its a matter of personal opinion, but the twins are jokes, they are a bullheaded wanna be macho man and a childish girl that thinks she is untouchable. They are also big threats, both things are not mutual-exclusive.
Going in order of your points to give my own.
The nobles are not in charge of the church, but fall does not fall only on the duke, he is the highest ranked noble and a part of the issue, but so are the rest of the nobles, there is no blameless people. By the same point of it being a medieval worlds, that means a good majority of the nobles that go away while the people are left to be sacked are useless, their lands are now in the hands of the twins, their riches just what they could carry, and they have no army to speak off aside from whichever of them that know how to fight.
Second and third i can combine for the answer, at what part did i say rowan is blameless or mentioned teleportation. Yes independent of corruption Rowan was forced to do bad things, he is guilty. And that has nothing to do with the point. Warden brings nothing to the table in his path that changes the situation for better or worse, it is a red hearing because the people that got away have noble blood but little else, names only get you so far, and the same way knights might be elite, it does not change that if the armies of the twins use the teleportation that thread is now cut and my point proven. Its not going to happen, and i can be proven wrong, but i highly believe that there will be no path where that is the "best sabotage",you sabotage things better by mitigating damage having someone loyal to rowan than gambling in an army of now unlanded nobles and knights walking around. Aside from keeping the high priestess unpetrified, that path brings nothing that would not be accomplished by survivors telling what happened.Either way the realms now know that demons conquered a major city.
Fourth,sure, a shame the man is, and i say this without having replayed recently, a dead man walking, all of his opinions on peasants aside, the man cannot even raise a blade to defend himself and his son is no genius, i can be generous and guess that whatever he has is not going to kill him quickly, but how long would that last? The best general might be uncorruptible, but is also a assassin away from being killed even if his infermety does not kill him fast
Fifth, i already gave my view on this one but might as well elaborate without trying to make this a wall of text. If they are the only real force left rosaria is doomed,better forces have been described already and even on a best case scenario only part of the nobles will be usefull and the rest will be people that have no war experience and will instead be making the efforts of the capable ones more dificult.
Once again, this is my opinion, i am neither a writer nor a fly on the devs wall to know their plans, but prefer to take werden's route as example of how rowan cannot fight the twins directly, his efforts there lead to the people that get away being the least likely to be usefull bar a few individual examples, rastadel still falls and the efforts are wasted.
The true sabotage is in taking control of the situation and setting the pieces to minimize the damage and grow the future ability, the twins are arrogant and only care to notice when rowan is foolish enough to belive that werden and outright helping resistence will work, putting the noble woman in control after corrupting her herself gives him a loyal pawn in the game, getting the female orc in power someone in the orc hierarqui that he can tame. If that is not to liking, then putting the anti-noble guy in control, for he is not corrupted, just pragmatic.
I don't disagree that rowan deservers to get his teeth kicked when he is stupid,i am one of the anoying people that pokes holes in the logic that exists to justify there being a game. I don't know how you play your Rowan, but the story all points to the fight agaist the twins needing to be slow and methodical, breaking their control while minimazing the damage. The Rowan that is "a good man"is the one that went to his allies and dealt with the twins in the prologue instead of going alone with no plan.The one we play needs to make smart decisions if he wants to win in the end.
Will i be proven wrong? Only the second game will be able to tell. Maybe that path is the set up for the golden ending where the twins lose with minimal damage, but i doubt it.