Carissa had inferred the general shape of this, of course. She hadn’t guessed the specifics; they weren’t knowable and weren’t particularly important. In this world, she could make things less bad by moderating Keltham’s demands; across worlds, she could make things less bad by being someone who would predictably be possible to use towards that end. T; the details of those other worlds were not necessaryrelevant.
This is not to say that it does not hurt to learn them. The most awful things imaginable from the perspective of a Carissa, both for Herself and for the universe, and it turns out that both of these things are of approximately equal importance to Her, in how She feels about them, which is in both cases much much much more strongly than any mortal could fathom feeling about anything. And She observes to all of the Nethyses out there that Carissa-the-god, in every universe in which She arises, will try to make Nethys glad of having where-He-needed-to-vary-the-formula erred on the side where the universe goes on and not on the side where everyone dies in a fire.
And relevant for everyone else, see this, that Carissa ran to Keltham because she hoped that he was possible to persuade to do something better, that her thoughts were of Keltham and how he deserved better than to be betrayed and annihilated, and of the universe and how it deserved better than to be destroyed, and maybe a bit that the Tropes wanted a story where she was able to meet him where he was - but the Tropes do, of course, want that, and whether that counts as everybody being threatened by the Tropes seems unknowable from here. She does not think Carissa Sevar decided anything in reliance on Nethys or Cayden, and they can see that to verify it.
She has nothing to say to Keltham, not really. She thought She might but She doesn’t.