Hi Rob,
The limit is currently set for 9 columns if the field is not required (as it includes blank as an option) or 10 column if the field is required. 10 was chosen as a number of column for the early access to reflect the more common Kanban use case and to produce reporting that wasn't overwhelming. Is there a number that would be more ideal for your workflow Rob? We are certainly still open to feedback on the Kanban reporting features and the way our users are making use of the reports.