[Raynor]

The Orcses who run off go under the trees, but not all of 'em. What happened to 'em?

I am not versed enough in English to nitpick on the very quote you gave. What it seems to me is that all orcs cast aside their spear or sword and ran off into the woods. If some of them didn't ran, I expect that they were very few in numbers, they kept or re-took their weapons (if they threw them in the first place) and continued to battle. But frankly, I see no proof any orc remained behind to contemplate Theoden and Gandalf.

The 'point' is that Eomer is saying the Dunlendings sound like animals, worse, like 'beasts'.

And Gamling doesn't disagree, although he looks more familiar with this language than Eomer. I see no reason why Eomer was distorting a fact. Do you think he did?

The sound of 'Dunlendish' is not merely 'unpleasing' to Eomer, it sounds savage.

These people were eating, breathing and living in hate; they were at war; they were stirred by Saruman. I could only expect that their "alien" language, as described in the appendices, would sound rather harsh under these circumstances. I find French to be very melodic, but I have no doubt a person can "bark" in French. While some people find Russian or German less than pleasant, to be polite, I don't presume they demonise the russians or the germans. Anyway, the dunlendings being savage is consistent with Gamling description of them.