Racial spy survival

[Vifarc]

I want to mod the spy and infiltrate missions of the spies.
Can it be? I don't see what file describe these missions.

I wish I could decrease the death when spying or infiltrating, and, to balance, decrease as well the level up and the opening of town gates. The decreases would be a little for humans and greatly for the elves (making them almost never dying, else being assassinated).