With regard to Aethyr, my inclination to it stems from this mathymancer post:
Responding to both this and
@mathymancer, I feel it's worth considering that the mere existence of Kislev's secondary Vortex implies some interaction between the network and the Aether. They're turning the raw stuff of magic into semi-divine power, and from the way Zlata talks about it doing so is well within reach. Four primary Waystones are involved in it, one of which is a contingency and redundancy component that was apparently built by Kislev later on for that specific end. Obviously she's not in the highest levels, and there's a lot of reasons her account could be incomplete, and likewise Kislev was once a pretty big name player in the human schools of magic, but still.
It's not even the only data point to that regard. Laurelorn, Athel Loren, The Forest of Shadows... A lot of big name genius loci have a lot of Waystones feeding them. To the point where it wouldn't surprise me if said places are the metaphyical equivalent of a wetland: Take a huge, living domain, saturate it with magic, and let the abundant life and slow-souls of that place do their living and in so doing filter out and cleanse the poisons that pass through them. Magic responds to the souls of those near it after all. I'm fairly firmly of the theory at this point that it's changed by human wizards as it becomes akin to them and they to it, and so in a forest it would likely be changed by all those souls, even as it alters them in turn.
Similarly, Taal having a waystone-shrines dedicated to Him would also be a data point. If gods who's nature includes "being god of this specific region of the world" are involved in the network, they might well be ideally suited to help soak up and decontaminate magic passing through their domain. Too big to overwhelm, to bound to their land to get caught in the stream and tainted that way. (This also might even tie into the prophecy of tainting Ice Magic forever, if something in the Ancient Widow means the mini vortex is possible, but Kislev either lacks some of what is needed to self-right taint, or the process introduced a vulnerability. to an extent, it may even be not so much a "prophecy" as a user manual complete with list of known bugs and vulnerabilities.)
For that matter, I feel like this could even tie into the local Gods of Sylvania keeping vampires down for centuries to an extent. It may not even require spending significant power to contain the vampire; Outside of the occasional intervention to deal with search parties and suchlike, they could just be...
existing at them, and so that same process of putting their weight on the world that usually aids Waystones instead is spent soaking up and purifying the metaphysical pollution that a vampire would require to be reborn.
I'll admit. This... got away from me. I meant to write the first paragraph, and somehow three more showed up after it. >.>
