Learn English – What’s another word/term for professional speaker

"would also be fine with me to coin a new word". My friend is a grad student in architecture. He tells me that both students and teachers pride themselves on making up words that no one notices were just made up. lol, so my suggestion is to make something up. Maybe innercore.

Maybe just core. although not made up, it would contradict Interface well.

Things that flow well in conversation (with Interface).

• Personal Space (though not one word)
• Control or Controlled Space (from Andrews comments)
• Innerspace (as suggested by Matt)
• Intraspace (as suggested by Andrew)

But personally I like core best.

The figurative sense of professional that you describe is perfectly fine, as long as you're careful how you use it--for example, you can describe yourselves as "projecting a professional appearance."

If that's not a satisfactory answer, consider using different words in different contexts: you have a refined appearance, give a polished performance, are classy in your interactions with the public, and responsible in your dealings with booking agents.