Same army,so yes. Just like in the old rules. I think.

Different Keywords...but I can find no rule that says a Hero can only lead models with their own Keyword, just in their own Army.

Thoughts?

Yep. Those heroes are part of the Isengard roster and can lead any warriors from Isengard if they aren't being used as part of a legion.

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"Draw your sword with a heavy heart, but swing it with a heavy hand"

Would you lose the Isengard army bonus though?

And are they allies or in the same list? Should probably just check my rulebook

They would keep the army bonus. All the Duland models are in the Isengard list just like how Helm and Eorl are in the Rohan list with Theoden. If there isn't a added rule that prohibits or penalizes using models from the same list together than it is fine to do so. I didn't see any such rule on any of the new Dunland models so it should be fine.

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"Draw your sword with a heavy heart, but swing it with a heavy hand"

I think the Isengard army bonus is that troops with the Isenguard keyword don't take courage test until 66%. But Frida and Gorulf don't have the Isenguard keyword. So my interpretation would be that they can lead troops in the list, and you keep the bonus, but if you get to 66%, Frida and Gorulf would have to take courage tests (while any uruks they were leading wouldn't). Anyone agree/disagree?

That sounds right to me.

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"Draw your sword with a heavy heart, but swing it with a heavy hand"