Being able to watch as sales come in is certainly satisfying all by itself, but it is much more important to be able to see where did we get each sale from and what were our main sources of customers. Knowing this will let us focus on the most profitable traffic sources and stop wasting our resources on ineffective advertising.
Piwik should show us detailed information about each tracked sale:
Piwik should also add sales manually in the tracker or edit existing sales.
Piwik should also log what products exactly where purchased in each sale and we should be able to see this information in the aggregated statistical reports.
please see the "Goal Tracking" plugin that provides 1, 2 and 3).
4) could be built a plugin to improve Goal Tracking plugin
Concerning adding/editing previous conversions, this is not supported as this would require more functionnality than Piwik currently has. Also, the only thing customizable by conversion event is the price, you can't customize the products that were in the sale. if you are interested in this please test Goal Tracking and submit a new ticket with your suggestions of improvement.