The real reason rituals have consistent failure states by the way, is because it's literally part of the Ritual creation process. I'll spare you the pages upon pages on details of Ritual creation, let me post a few things from the book:
"Rituals are Absolute: Whereas spells frequently give bonuses to tests, and the ultimate results still hinge on a die roll, rituals have absolute effects. If a ritual is successfully cast, there should be no question about what will happen.
Rituals are of Consequence: Beyond being powerful, and even beyond having Consequences, rituals are of consequence—they change lives, lands, and circumstances for good or bad." RoS Page 169
"As a player, your first step in ritual research is to define your goal. What ends would your ritual bring about in the best of all possible worlds, and what casting characteristics would it have? The written expression of this goal is called the Ideal. The Ideal is defined just as a ritual is, with all the same statistics. Begin creating the Ideal by writing out the following ritual characteristics:
Type: All rituals created according to these rules will be of the Arcane type.
Arcane Language: This is typically Magick, though if you know the Daemonic or Arcane Elf language and have at least one measure of skill mastery in it, you may choose either of those instead.
Description: What happens if the ritual is successfully cast.
Consequences: What happens if the ritual is not a success.
Ingredients: The material elements that must be assembled and used to cast the ritual. Conditions: Requirements of timing, location, target, or anything else."
"The following modifiers apply in all iterations of research.
–10% If, in the current Draft, the Consequences of a harmful ritual are—in the GM's judgement—less severe than having the effects applying to the caster rather than the intended target.
+5% If the currently operative Consequences include the caster's death.
+3% For each Ingredient and Consequence in your current Draft that is linked to your ritual's effects.
+3% If you have the second and final measure of skill mastery in Speak Arcane Language (Magick).
+3% For each of the following talents you possess: Aethyric Attunement, Dark Lore, Dark Magic, or Luck.
+1% For each of the following skills you possess: Academic Knowledge (any, with a bonus for each) or Magical Sense."
There is a list of possible consequences, ingredients, and a number of other considerations and other things that I've cut out, but the reason Rituals fail the same way is similar to why they succeed the same way. It's part of the creation process. You can miscast while casting a ritual, no doubt about that, but the Ritual's effects are absolute once it has been completed. It has to be, otherwise it wouldn't work.
