Creature landing sound counts as a footstep
It seems that Cliff Racers and Betty Netches and Kagouti...etc corpses falling down on the ground sounds count as an "Effect" in vanilla Morrowind, but in OpenMW they count as a "Footstep".
Note that vanilla Morrowind doesn't clamp sounds correctly so when changing sound settings (for example footstep sound to the lowest and effect sound to the highest) you need to reopen the game so the changes will stick.
I couldn't confirm what Bull Netch corpse falling to the ground sound count as in Morrowind but in OpenMW it counts as a "Footstep" as well.
Edited by Alexei Kotov