What has always been needed is bishops who are willing to do their job. The supervision of priests cannot be the responsibility of the Vatican. (See Jethro's advice to Moses in Exodus 18.) The responsibility of Rome is to light a fire under the current bishops and use better judgement on the selection of new. The multitude of problems in the church for the past 50 (and they go way beyond the priest abuse problem) has not been because of a lack of documents, shortcomings in structure, problems with canon law, etc. It has always been a problem of personnel. Put good people in as bishops and you will not need more documents, changes in structure or revision of canon law.
You know even instituting a document log in a database in re: complaints and subject manner might even help.
It seems there is a problem with authority and structure and scope of responsibility.
Maybe hiring someone other than an ordained priest might be helpful.