Can an ag-grid event be triggered manually? - YES

From our API docs:

https://www.ag-grid.com/javascript-grid-api/#events

dispatchEvent(event)	Dispatch an event through the grid. Useful if you are doing a custom cellRenderer and want to fire events such as 'cellValueChanged'.

The contents of the event param are explained here:

https://www.ag-grid.com/javascript-grid-events/#properties-and-hierarchy