Official comment
You can easily do this, with or without consolidating all of your Campaigns onto a single map.
In ONTRAPORT Campaigns you can select what happens when a Trigger is activated. And, you can have the same Trigger on as many maps as you like.
In it's simplest form a "reporting Campaign" might have just the Triggers, then an End element after each one. Set the Trigger settings to "Any Contact in Account" for "Who can activate this trigger" and under "If Contact is already on map" select "Add here again when Triggered". Any Contact who activates the Trigger will increment that Trigger's stats on that Campaign, and be part of the number of Contacts displayed on the End element. Clicking the number on the End element creates a Group of the Contacts who are there.
You could add a Wait forever element after the Trigger as well, or add other elements to the Campaign Path below the Trigger. It's up to you. The Trigger will count each time a Contact is added to this Campaign just as it does for it's original Campaign.
If you want the reporting in one place, the alternate method is to add all the Triggers in use to a new Campaign, and have an Action element under the Trigger to "Add to Campaign". Remove the Trigger from the original Campaign and all Contacts will pass through the new Campaign's Trigger before advancing on to the old Campaign.