I think the game help before the ritual is misleading some people, I will try and make it more clear.
Here is a hint for gameplay:
The helpful and harmful runes don't ever change, they are hard-coded per demon/per phase.
So hopefully your first few playthroughs you learn and memorize the correct runes for the given demon/phase, then after that you can work on finishing the ritual more quickly to try and get 100%.
Hope that clarifies!