Teams can have complete dashboards and still disagree about what a lead or conversion means. Shared definitions and consistent campaign naming make the numbers easier to use.
Begin with a short list of decisions the report should support. Then identify the source for each metric, note known gaps and check that tracking behaves as expected.
A reporting system should make questions easier to answer. Review it with the people who will use it and remove measures that create noise without changing a decision.
Make the next step clear
Choose one part of the journey, give it an owner, and check whether the system is doing what your team expects. Then build from what you learn.
Discuss your workflow