We know cascade failure is a risk of the model. If were a risk as severe are you are trying to portray it, far more sections of the Empire than just Sylvania and the Drakwald would dhar-infused hells well on their way to become a new chaos wastes. Instead the network has stood for millennia with only occasional maintenance. The Belthani couldn't build waystones and they were driven out after only five centuries.
I mean, to slightly caricature, the discussion went:
DP: What would Eltharion think about our new Waystone?
Me: I think he'd like it, because he expressed concern about the vulnerability of the original network and our version has a backup transmission so is less vulnerable.
Others: the network isn't actually vulnerable.
Yet others: Eltharion was wrong/ has unrealistic expectations
Those responses, to my mind, miss the point. By one of the factors by which I believe Eltharion criticised the original network, ours, in the words of Boney is a 'tangible improvement'.
You may think this isn't a meaningful issue. I would suggest that Eltharion, the person this discussion is about, disagrees. Otherwise, what else do you propose he meant by not dealing well with deliberate sabotage? The danger of cascade failure is just about the greastest vulnerability to that we've seen.
It doesn't matter objectively how great the original Waystone network is, only what he thinks. He set it as a success criteria. I think we met it.
You could alternatively have Mathilde go and tell Eltharion he's wrong to care about this, but I don't think she'd get very far.