Looks like ffmpeg is choking on your audio while trying to copy it, it’s a known open defect in ffmpeg.
Meanwhile add -max_muxing_queue_size 4000 to your ffmpeg-video line it should fix the issue.
ffmpeg-video=-ss 0 -max_muxing_queue_size 4000 -vf yadif=0:-1:1,hqdn3d -vcodec libx265 -preset medium -crf 21 -map 0:v -sn
If that still fails, try increasing 4000 to 99999
You can also remove the handbrake-xxx lines since you aren’t using handbrake
We’ll try to put in a detection for this error and automatic correction in the next build of mcebuddy
EDIT: Cross reference: Ffmpeg Bug - Too many packets buffered for output stream