Random observation in this general area: Regular triggers provide the
field Trigger *tg_trigger in the trigger data, which allows you to get
the trigger name, OID, and such. Event triggers don't expose anything
comparable. That should perhaps be added.
Also, as I'm maybe about the fourth person ever to write an actual event
trigger, I have a usability report of sorts. I found it confusing that
the trigger timing is encoded into the event name. So instead of ON
ddl_command_start, I was expecting something more like BEFORE
ddl_command. There might be a reason for this design choice, but I
found it a confusing departure from known trigger concepts.