Hope Rekindled has: Action: Reduce the cost of the next event that has a Valour trigger you play this phase by 2.

Can you use this action to reduce the event's cost if you are using its standard action, rather than its Valour action?

I don't see why not. It still has the Valour trigger even if you're not using it.

That's my thinking, just wondering if there were any reason to think differently.