Stargate Origins

Kelly Vint Castro (American Agent) previously played the young Catherine Langford in Stargate (1994).

Catherine goes from not being able to speak at all with the natives on the planet to being almost fluent at it couple episodes later. Even assuming that she's a fast learner it's questionable that she has any previous knowledge of ancient Egyptian languages, otherwise she would have understood at least some words when first talking to Kasuf. However, Daniel experienced the same effect in the first movie. It was because the vowels were pronounced differently than he realized. It was a language nobody had spoken in over 2000 years.

Referenced in Stargate: The Definitive History (2019)