The issue is demonstrated in the video from the thread: #110

I just have spent an hour to figure out how it works by comparing working audios and not-working. The result: system works properly only with STEREO audios like this

and acts wobbly, as on video, with this

So the decision outside of the mod is to properly prepare files (in audacity just a few clicks, or with python script, i did that on my audio generating server), inside the mod - probably write a stereotizator using ffmpeg.