A report is defined by its data, but this is not enough.
We also need to somehow define in the report - a date format (for graphs it may be 'Week 2' but when displayed in the UI it would be 'Week of January, 21st') - legends for graphs (eg. '%s visits' or '%s distinct keywords') - title for the report (eg. 'Distinct keywords' 'Countries') - titles for graphs (eg. 'Evolution of the number of %s', or simply use the report title as is) - existing bug, in Visitors > Overview, the graph always shows the english word 'days' eg. in french: volution sur les 30 derniers days - other..?
Also see #5546
This has to be specified first as I think I may have forgotten some points.