Alicornutopia

The infirmary is not guaranteed to the same standard as the security, but it is staffed by people who will probably be able to make some progress if you get there. They do not tend to rush out and ambulance you in, you have to go to them. Emergency medical teleport to Milliways is not a bad idea if you can pull it off.

That reminds me, a question about the Milliways language effect: If someone came to Milliways who wasn't deaf and knew no sign, but had lost her voice and couldn't speak either, would Milliways be extremely convenient at her or would she have to get by with writing?

She wouldn't be able to talk, but she could understand sign others used at her. At authorial whim she might be likely to encounter telepaths.

And would also be able to understand others’ speech, presumably. But they could not make up their own sign language and be automatically understood, like with fairies and Arabek gods?

Right, no spontaneous interpretive dancing will the Milliways translation effect handle.

Since Cam doesn’t really understand this in-thread, could you explain why naming Essence was supposed to help and how?

Naming them allowed summoning them, and they were the only thing big enough to eat the greater being and take it home.

Oh, I had misread part of that. Cam named and summoned all of the previously unnamed parts of the combined demon-being? If I now understand correctly I’m surprised it could even be summoned without destroying London even if it was trying to prevent that.

Yep! Cam did summon all previously unnamed parts of the demon-being! The idea is that Essence was being summoned willingly. Uraziel relayed information before Cam summoned Essence, and Essence had incentive to want to be summoned.
The greater being was intentionally destructive and hurt and angry. It was a fragment that had rarely been summoned, so had never developed a personality or a mind. It couldn't think on it's own, didn't know how to control itself and didn't care to learn.
Essence could choose to be destructive, but didn't choose to be. Essence is closer to how demons exist in the Other Place, which gives them an advantage in terms of lucidity and self control. Even so, there will be effects from Essence's presence, just less immediate ones.

Essence wanted to be created, because now magicians can't create any new demons. Any demons Essence absorbs and does not release will also be protected from summoning. Since normal magicians can't safely summon Essence, this protects the majority of the Other Place from them.

There should be a thread with the full list of all worlds ever, links to their worldbuilding threads, their authors, and maybe even nicknames of important templates' instances. I would find it useful enough that I might even volunteer to do that thing and keep it up to date if nobody else does.