On a positive note regarding the 32-subtitle revelation, it appears that all of the playback issues I was having with tons of audio tracks, many of them lossless, all went away once the subtitles were limited to 32, so it may have been general non-compliant disc issues. So the good news is it's looking like we're not necessarily pushing the limits of Blu-ray on the audio front. Keep in mind, I haven't tested a disc with over 32 audio tracks*, so if that's actually a possibility, that would still need to be tested.

EDIT: *I did test with over 16, so I'd say we're safe up to 32.