Since I've lived with dogs my entire life (my family has never not had at least one, and we almost always have two), and walk them as a volunteer at my shelter, and I walk neighborhood dogs for a job, it's safe to say that I'm with dogs. A lot.
And when it comes to dog training, I see everyone always using English words as vocal commands. But it's been well established that dogs don't respond to words - they respond to the physical action associated with that particular sound. When we move a treat so far backwards that they have to sit, and say "sit" while doing that, and then later they will sit after being told "sit", they're not responding to the word's meaning itself. They've come to associate a physical action (sitting) with that syllable.
The reason behind using English words is not for the benefit of the dog, but for the human. A dog can be trained to sit after hearing the word "lala", but us humans can only respond to words that have, in our known language(s), the meaning of the physical action.
So I'm thinking - when, in the years to come, I have a dog of my own, I think I will try to train them using nonsense words. Because I don't think English needs to be used any more than necessary.
(Either that, or I'll use Latin. "Sede." "Descende!" "Veni!")