Simulating MPE with MIDI Transformer?

I have a non-MPE keyboard controller and a synth that can receive MPE data. Using the MIDI Transformer insert, I can take (live) notes from the controller and randomly spread them across channels 2-16, so I was hoping I could insert other per-channel MIDI data (e.g. pitchbend) for polyphonic expression. However, the synth will only respond to other data received on channel 1, which is global. I can see in the MIDI Monitor that pitchbend is being sent on channels 2-16 but it has no effect.

I assume it’s just not possible to simulate MPE this way but I’m interested to understand why, since, as I understand it, all MPE does is transmit note data on different channels and that’s exactly what the MIDI Transformer is doing here.