Yup. The Rohirrim see this Elf standing there bitching at this maybe-Gondorian, maybe the King of the West, maybe just another weird Ranger, and the two of them are obviously arguing in a foreign language like the Rohirrim don't matter (which is how Men see Elves - stuck-up and isolationist, ignorant of the plight of Men), and then the Ranger says something that cuts straight to their own philosophy.

Good point actually. It's been a while since I've watched these films and I remember this scene being emotional but I don't think I thought about it too hard beyond that. But you're right, he probably purposely says that in a language they'll understand, to be on their level and an honest leader.