Anders entire plan hinges specifically on Meredith annulling the Circle. He needed it to happen, otherwise the mages aren't forced to fight back and rebel and murdering Elthina accomplishes nothing.
Also yes you can call Elthina innocent because the entire Chantry is not the Circle, nor is she responsible for the unsanctioned abuses of the templars. It's also not clear that she was the only priest inside. You could just as easily assume there is almost never anyone in Kirkwall at all given how few we see.
The Chantry in general is responsible and Elthina was knowing it when she was joining the chantry. Its like saying a soldier is innocent because he didn't kill like his comrades. He shouldn't have join if he wanted to be 'innocent'. She was either very ignorant or very smart, seeming innocent while ignoring the suffering of Kirkwall and preaching all is well.
Also you compare a scene to general gameplay. Sure we see less people when walking around but what we see during scenes is fact, for example in Sebastian scene where he shoots an arrow to chanter's board the background is full of people, the same place has few people when we are controlling Hawke. So whoever the scene shows are in side the chantry is true, claiming otherwise is stretching.
What? Of course it can. Even all the mages in Kirkwall themselves think so. The reason being that he was specifically trying to provoke an annulment so the templars would try to kill them. That's specifically trying to cause the same ethnic cleansing you railed against.
And even if that wasn't so, his goal isn't necessarily a worthwhile endeavor. A world without templars could be much more dangerous than the one he wanted to tear down.To say nothing of who he harmed to get to it.
And even if supporting the Circle System was inherently anti mage (it isn't), his decision to specifically kill innocent people so the templars will kill more innocent people so that a war where even more innocent people will be killed can and will still be branded as disgusting and deplorable. He probably created a much greater evil than the Circle was.
Anders destroyed the chantry in a way that no one else could be blame for it but himself. He is standing there, declaring wars on Templars and destroys the chanty when he is done with that speech. Meredith does what you think is disgusting, the funny part is Anders is glowing and his voice has changed right in front of Meredith and other Templars yet they seem to ignore the abomination responsible in front of them and go for innocent mages of the circle. An order like this with chantry on its head totally deserves what Anders did. Provoking is irrelevant, if templars promote a damaged person who has become a monster as knight commander that is entirely their fault. You quoted first sentence of my post and ignored the rest which was the elaboration. Anders wants to overthrow the chantry and its leash on mages, if you call that 'evil' then that is your opinion because it is not a fact, he simply has a cause.