MYTH: A dialect coach speaks many languages fluently.
It certainly isn’t a requirement for superb work.
In simplest terms, a dialect coach’s job is to ‘help one person sound like another.’ This entails being able to analyze a particular ‘sample’ of spoken language and then guide another person (most typically an actor) in hearing, duplicating, and ultimately integrating the components of that ‘sample’ seamlessly into their work. The job demands a keen understanding of how a particular set of words (the script) needs to be spoken (for authenticity and accuracy) rather than an ability to converse fluently in a foreign language.
There are of course times when a coach will need to have a firm grasp on basic elements of a particular language in order to deliver a good product, but rarely will this require fluency.