Well, I think there is. It is called roleplaying. When a difficult situation arises, you just have to get together and talk it through in character.
The point is not that RAW has no official method. The point is that the Order do not have a pre-set method. There are the basic and strict principles of the Oath, and there is the precedent of previous tribunal rulings, of which the books only have a few and the rest must be invented like any other aspect of the game world. The rest is roleplay.