Currently there is no way to show custom success and informational messages during Automation Service task completion. Example code for Success message : return new TaskExecutionStatus(true, "Export to Html completed successfully."); This message does not show during task completion.
Only error messages could be displayed during task completion. Example code: return new TaskExecutionStatus(false, "Export to Html failed. Destination folder not selected."); This error message gets displayed suring task failures.
It would be nice to show success and information messages during task completion.