That’s the definition of eternal… the Kyrian aren’t a force of life, they’re a service arm of the afterlife. They have a Purpose that is in eternal need. Evolution doesn’t come into play. Their very existence is in the conductance of souls without judgement or prejudice. They aren’t supposed to change in that.
It’s our job as mortals to be the agent of change, mortals who still have a living stake in restoring the Kyrian to normal operation, not to push them into something they are not.