Detecting Observer Chat Events

Is there anyway to detect when an observer or referee says something?
TriggerRegisterPlayerChatEvent doesn't seem to work.

Basically, I want observers to be able to use chat commands but I can't figure out how.

only if do custom observers. usual observers can't trigger anything. (afaik)

I suppose I could add 4 slots and make them normal players, but is there anyway for them to be able to see observer chat?

only if you do a custom chat.