I created a TurboGrafx-16 module in Furnace that uses the synthesizer to simulate slap bass, using the "fade" option on an instrument to make it transition quickly from one waveform to another.
It's known that the TG-16 makes a buzzing sound when you switch waves on the fly. When I exported my module to VGM, I noticed that the song was still trying to update the wave form of my bass instrument even though the waveform had stopped changing, making the bass channel buzz for longer than expected. Maybe there could be a way to detect when the waveform changes or stops changing.

Note: I used VGMPlay 0.40.9 to test the audio.
wave_switching.zip