The UI doesn’t send commands (unlike some other tools like Maya) so there isn’t necessarily a 1:1 parity. Have you looked at the example python script provided in /Engine/Plugins/MovieScene/SequencerScripting/Content/Python? That shows you how to create and run a batch render from Python and configure it for an output (png image sequences maybe?)
Blueprint’/Composure/Blueprints/ComposureExport.ComposureExport’
_C does stand for class, likely when calling SetImageCaptureProtocol you would have to transform that above reference to:
‘/Composure/Blueprints/ComposureExport.ComposureExport_C’
But you may need to play with both options to see which one it will take.