For simple iteration, users of the module provide a JSON file as the config which is mashed together with the DEFAULT_CONFIG to produce the final configuration ruleset. It's trivial to iterate over parsed JSON and this value; going line by line would be much more code and I don't feel it would really improve anything.

But going from your example, it could be that keys are called MATCHER_DEFAULT_* and then iterate the JSON and put keys together with string concatenation. Do you feel that would be a significant improvement?