One issue with the macro-prudential approach being pursued would be to find the appropriate balance between a rule-based, formulaic approach and the regulatory discretion for determining the course of action.
It is quite possible that the sense coming out of the macro analysis or stress tests will be in the nature of potential leads without any conclusive evidence and therefore not amenable to rule based approach. However, this should not lead to inaction if there are overriding considerations of financial stability.