Answer me this last question.

Prior to the whole wiping incident, was the progress of the run endangered in any other way aside from a people speaking a different language to each-other?

I agree, the whole wiping thing, or even argumenting would not need to happen but if their conversation isn't hurting the run itself and they keep doing what must be done just let them do their thing.
I've played games which relied on partymechanics heavier than this one, I've partied with people from all over the world speaking countless of languages I did not comprehend.
But as long as their converations did not hurt the party mechanics in any way there was no reason for anyone to speak up about it and in my experience, if they said something that was directed at me or any other person in the party or alliance that doesn't speak their language, they will switch to English.

That said, what happened to you is fairly exceptional (I hope).