Ridiculous! In English "come down" means exactly what "descend" would mean. As a matter of fact the Teutonic root is considered more authentic than the Latin derivative. Then why would such an answer be rejected?
"Umbra de caelo descendit" could correctly be rendered in English as "Shadow comes down from the sky".. (since Latin does not use definite or indefinite article...
I am curious about the meaning of this. If the sun is shining, I think of a shadow as being cast by the sunlight and lying on the ground, not as descending from the sky. I see that some of the other comments mention the idea of the shadow being a ghost, but I do not know enough to speak to that. The only way this makes physical sense to me is if something, say a cloud, gradually obscures the sun. Then the shadow would grow more widespread, as everything on the ground would come into the shadow of the cloud. That is at least the image I get from this statement. Did the Romans think of it in some different way? Is a sentence like this one that they would have said?