Communication Breakdown

If a dignitary from a non-Anglophone nation speaks a language that is not his native tongue, yes, you can introduce grammar mistakes and such. Even an educated man may stumble in a foreign tongue. If you have him communicate in his native tongue and have someone from his own or another non-Anglophone country translate for him, this rule also applies. Translators are people and people make mistakes. But if you have him speak in his own first language and then mention that the English lines we read in the script are the subtitles FOR THE LOVE OF PETE don't introduce any 'foreign speaker' grammar mistakes. It's his native language. Unless the character is uneducated he probably speaks it fine. Unless the person creating the subtitles is a character in the story (ala Monty Python and the Holy Grail) subtitles are pure knowledge. Grammar and word choice mistakes here will make the production company look dumb, not the character.

Formality Flaws

Picture in your mind a proud, anxious young man in a job interview. Think about how he'd like to sound.

"Good afternoon, sir. Thank you for meeting me. And for this opportunity. I really appreciate it."

Short, flavorless sentences. Few contractions. Formality.

Every year I read scripts where characters speak like this all the time. It's the cinematic equivalent of a Martini so dry they skipped the water *and* the alcohol.

Your script is part job interview. True. But it should never sound like one. Even calm, respectful characters speak with creativity. If you doubt this, see Larry Crown. It's a masterwork of good characters that sound different from the lead and from each other.

Life isn't one long job interview. Neither is your next great script.