Yeah! She’s been saying “injurylike damage” to mean “the precise set of things that a channel or a Cure can fix”, because Blai described those to her as for acute injuries and not illness or, say, the kind of diffuse organ damage that accumulates in the bodies of older people, or for any of a thousand other reasons that put the wrong kind of strain on a particular pathway or process in the body until it starts to break down.
She's still wrapping her head around it, because it's not as though positive energy doesn't get small-scale dysfunction, it just - only seems to target it if it's associated directly enough with an acute injury? And it doesn't seem to be able to "see" or land on the damage that's smaller than a single cell, the "burning" of the tiny parts inside that she's now learned are what provide instructions to every cell on how to be a part of a body, like a tiny library. If it were less damage that this - a lot less - it wouldn't kill him but would eventually cause tumors, as cells followed their corrupted instructions and went off on rogue missions. She checked and confirmed a theory with Dr Chadra that this isn't totally disanalogous to ways that older people's cell-libraries can gradually accumulate mistakes, because the library needs to be "copied" every time a cell splits into new cells, which is constantly, and the majority of people won't die of a tumor but it's a significant minority that do, and even elderly folks who die of something else first - a bad heart, or a winter pneumonia they're too frail to fight off - often have the beginnings of tumors.
Anyway they're not going to have to worry about that in this case because the damage is a lot worse - not just garbled library-instructions that will send cells off on rogue missions, but instructions shredded to the point that the cells will just die the next time they try to divide. Which is a serious problem because many parts of the body rely on continually dividing cells to replace ones that are destroyed. Skin, for example, or the lining of his gut, which is...more or less completely "dead", not in the sense that all the tissue is already dead now but in the sense that there's no remaining underlying vitality to keep replacing the "disposable" cells, that in the ordinary course of things are expected to die and be replaced on the scale of days or weeks. The Cure spells seem to consider the surface damage - areas where enough cells died and sloughed off to leave a internal wound - as injurylike, but it ignores the underlying lack-of-vitality, so the wounds are just going to keep reappearing. The bone marrow is the next biggest problem – the vital cells in blood, the ones that help it move the vital part of air to where it's needed, usually last weeks, but a lot of Leareth's were damaged, and he has no innate capability to make new ones because the libraries in the bone marrow cells that would divide into new blood cells are too corrupted to allow this. The bone marrow also makes the cells that cluster on wounds to form a clot and then a scab, and the cells that fight disease, and both of those turn over faster, so Leareth has dangerously few already. Cure spells do, actually, seem to put the vital cells back, and if it's not enough they have the capability here to give Leareth someone else's blood - it's actually an idea Shavri had had, but in Valdemar it's at the risky experiment stage, different people have different flavors of blood and the wrong flavor will make someone very ill in the same way that some unlucky people get very ill from a bee sting -
She's very grateful that the damage to Leareth's brain does, significantly, seem to be "injurylike". Brains are delicate organs that can't go long without the vitality of blood reaching them, and even a little bit of inflammation and swelling, in the confined space of the skull, will start squeezing the vessels that deliver that blood, which is a rapidly escalating vicious cycle because starving the tissues causes more damage and more swelling. At the worst point, Leareth's brain was...pretty destroyed, actually. But the Cure got all of the gross damage and reset the swelling! It's just that it's going to keep coming back, because the cause is corrupted libraries in the cells lining every blood vessel in Leareth's body, and the cells so corrupted aren't going rogue in the sense of becoming tumors but they are sending all sorts of alarm signals - say, imagine a messenger trying to relay messages in an emergency, but they're also delirious with fever and making up additional emergency messages at random, and so are all of the messengers along the relay -
The Earth doctors cannot actually make Leareth heal. They can fight infections for him - they’re giving him drugs that poison only the diseases and not him, or, well, probably some of them are poisoning him a little but it’s worth the risk when his innate defenses are so weakened. They can do remarkably complex surgeries - to repair injuries, or fix internal problems caused by diseases or old age - with surprisingly low risk to the patient, but "surprisingly low risk" is still a lot of risk for a patient as sick and fragile as Leareth is right now, and in any case most of what's wrong with him isn't the kind of - gross structural disruption - that a surgery can fix.
The plan right now is to give him ALL the drugs that kill infections, and other than that it's just "supportive care", which is a term that made perfect sense to Shavri - in Valdemar it would just mean, like, keeping a patient comfortable and helping them eat and drink and cleaning them and moving them enough that they don't get bedsores - but what incredible options they have here! On top of all the artifice to support Leareth's heart and lungs, they have extremely specific drugs for EVERYTHING! And their artificial Healing-Sight is in many ways "narrower" than Shavri's Sight, but it's so precise – they can exactly track improvement or deterioration on dozens of different measures, that Shavri doesn't begin to understand how to tease apart even if her Sight can perceive the underlying qualities at all...