Causal powers maintained if simulation low-level
The person whose neurotransmitters have been replaced still understands Chinese because she still has the right causal powers; she just needs some help from the demon.
The demon simulation is low-level enough that the relevant causal effects—the physical simulation of neurons—are still initiated, and so intentionality is maintained.
John Searle 1980a, 1980b, 1990b.