A key point is that the central executive (the core, which controls the flow of data between slave systems) is a trainable neural network itself, which learns to generate the "mental actions" that control the flow of data between slave systems (like short-term and long-term memory), rather than rely on fixed rules to control the flow. This allows the system to generalise.
(Some of the training itself doesn't seem to be that similar to training a human child, though. It's instead tailored to the system's architecture.)
I'm excited to see how much richer this and similar systems will become, as researchers improve the neural architecture and processing efficiency. Will we see truly human-like language and reasoning systems sooner than expected?