Council of Elrond

Theo wrote: ↑Tue Jun 19, 2018 4:42 am Is your reasoning that the effects from Akhôrahil, Dwar of Waw, Hoarmûrath, Ren, while having an opportunity to be canceled, aren't themselves the Nazgul event that caused the effect?

An effects (or results) of events, are not themselves an events that cause the effects (or results) .

Theo wrote: ↑Tue Jun 19, 2018 4:42 am Something can't be canceled after it is resolved?

I do not think so.
Canceled may be ongoing or declared effects, not implemented.
Searching Eye may cancel an ongoing effect like effect of Stealth. The effect is not implemented to a company, rather a company is under this effect.
Searching Eye may not cancel a result of a resolved Concealment (cannot reactivate already canceled attack).

Bandobras Took wrote: ↑Thu Feb 15, 2018 2:19 pmAutomatic-attacks are not a hazard that targets the company.

How about on-guard creatures? Could Great Ship be used to cancel an attack created by them?

I think that it can be used to cancel such creature as whole (along with all its attacks and with non-attack effects).