By they looks of it they changed the word 'async' to 'actor' because they thought it was cool not because it actually uses the actor pattern. Which to me seems to be namespace pollution.
Unfounded guess, they probably didn't want to bump into the new C++ keywords for async/await.
If I were designing it today rather than in... 2008?, I would use the terms 'async' and 'await' because they are a lingua franca now. And for a modern audience that already knows what promises are it probably makes sense to start the explanation with that part. But the thing as a whole was intended to build lightweight asynchronously communicating sequential processes with private state that can be run locally or in a distributed way transparently, restarted on failure, etc. I don't think the choice of terms was obviously a crime at the time.