It is currently not possible to use EnumWrappers.EntityPose in the most recent version v5.1.0 and dev builds.

WrappedDataWatcher.Registry does not have a serializer that will make it possible to use EnumWrappers.EntityPose and WrappedDataWatcher itself cannot work with EnumWrappers.EntityPose, so you have to use enum EntityPose from NMS directly.