PSA--if anyone's trying to make a super-internationalized Blu-ray, Project Threepio is big enough to make a difference toward your non-video maximum bitrate (8Mbps). If your audio options push you over 7Mbps (if you have lots of lossless tracks), the subtitles will definitely push you the rest of the way over the limit. tsMuxer doesn't warn for this, your player will just behave badly.

So you might need to choose between multiple lossless audio options, or global subtitle support. My bad disc had five lossless English tracks and all languages (dubs and subs), and I'll probably cut it back to one lossless track just to be safe.