I don't think the localized parameters should be used to animate clouds, or did you want to lower the cloud in time? It's just the area where clouds occur.
If you want to lower clouds, I would animate the Y of the fractal and if no or a little movement of clouds is necessary, also use a distribution shader with an identical animated height restriction. But the localization should be bigger than the area you want to traverse with the cloud. Localized is a sphere, more or less, you can also use a soft SSS, which is a vertical cylinder. Theory, never done this.