@AzazelSlayerRaka is a tourbillon of dreamworlds and Ilunabar cares little about how "good" these dreams are. This is how it has been for 6 months now. This was literally her contribution in the creation of the universe.
I mean, she literally invented the concept, it is implied before mortals wouldn't be able to dream (and therefore have nightmares) at all.
I do not see what you are talking about, about "nightmares" going loose, that is not how the arpeggio or raka works, and even if it did happen, so what? Ilunabar herself has let loose an eldritch, dream-eating being in dreams once.
I can't work with just "good" dreams, that is never how things were meant to be, the Raka has always reflected the person's unconscious and some of the sectors, like Reave, Mirage, and Labyrinth all work on the pretext of nightmarish worlds.