You’ve got a point, but I don’t see what ‘speed’ means for these, since they are not standalone abilities and are cast immediately when Emerald Dream is.
Alas, communication and clarification, as well as documentation, has been a week point, but I agree that we could keep that for reference.
Hmm, come to think of it, they might have fixed it by no longer having Nightmare as a Shadow ability.
Is it? In Mercenaries, if memory serves, the speed of an ability with the ‘Discover’ keyword depends on what it discovers, unlike Emerald Dream, which has a fixed Speed… Although dicsovering has been messy, reminds me of another old problem, for example: Fish feast doesn't give HP if Finley discovers it (I wonder if it still persists, haven’t tested it yet — although it has been present for some time throughout a few patches).
As for other Ysera’s abilities, by the way, Verdant Breath still broken, as I’ve written above — tested in 24.6.