Okay, I've got the English mono track synced! I was also able to clean up a handful of very minor issues, like that pop you heard when Arthur reaches for the Holy Hand Grenade.

So, just to recap, here are the key differences from the Blu-Ray:

DONE:

Cut Anthrax scene extension

Default track is lossless mono (single-channel DTS-MA with 192kbps core)

German subtitles

PLANNED:

Original Criterion mono commentary track (lossless?)

Original Criterion mono Japanese dub (lossless?)

Full Japanese-back-to-English subtitles

I imagine this will be slow going again. Luckily I believe I'll be able to sync both remaining audio tracks with a single pass because they're from the same source.