I have a couple of suitelets that user interacts with. On POST, the suitelets create queue records. A UE script on the queue records start a map/reduce script that processes the queue records which in turn creates transactions. When the map/reduce is running, all records it creates are tagged with "created by" as the user that interacted with the suitelet. Is it possible to break the chain of user somewhere convenient so that the map/reduce is executed by a "system"-user that I control? It's in the interest of getting a number on how many transactions are created manually in the UI. (may need to go the system notes route)

let a scheduled map/reduce script handle the queue records

Good idea! But I like the responsivenes of starting the script immediately on demand. I'm contemplating adding a UE-script that fills a field on transactions that indicates if it was created in the UI for this purpose