The language is less than clear, but I think the intent is that rituals are always cast with a stress die. But with contradictory language it needs to be House Ruled, because different people see it differently. I think even just using vis to power one's spells should be an automatic stress die, with a botch chance of 1 + pawns of vis used, but that's not the case, either.
Again, multiple ways to reduce botch dice. Those ways suggest older magi, a lot of spell mastery, maybe a HR Ritual Mastery spell mastery ability, and you can knock down the botch dice pretty quickly, what one would expect from an old covenant like Durenmar.