Take a video, put it in a Composite shot, Right Click> Speed/Duration and set to 200%. It plays fine, twice as fast and with higher pitched audio.
Add the Pitch Effect and play it again - don't even change the pitch.
Remove the Pitch Effect and embed the video further; make a Proxy of that Embedded Composite to 'bake in' the speed change.
Add the Pitch Effect to the original composite - now pointing at the proxied embedded composite - don't even change the pitch.
Various method of preprocessing the video both before and after adding the Pitch Effect made no difference - Proxy, RAM Preview, both - but I couldn't get it to play smooth audio.
I wanted to lower the pitch to make the audio sound normal, but this doesn't seem to be the way to do that.