Add new column to 800xA alarm and event list
AFAIK not possible (but not a bad idea in itself).
I suggest that you ask your regional ABB sales representative to file an enhancement request.
For the time being, please have a look at the Alarm Comment function. Such texts will be retained by Event Storage and secondary Message Log; eg IM for later extraction.
It is important to remember that an alarm is volatile information which will be lost when the condition is inactive and acknowledged. Comments are kept in event storage until it wraps. Subsequent alarms will unfortunately arrive with empty comment.
Hint: object description might be a workaround... don't know if it support write for operators though.