OK, Mavimao, I'll be sending you the scripts as I finish them :-)

As to the third track, I tested the MKV in my Samsung BD Player and it plays just fine, including the mono mix, so there's probably nothing technically wrong with the track and your hardware players probably just don't support DTS mono. If I knew this, it would have been good to include the mono mix in AC3 (the one in the AVCHD is only like 100MB) but it's too late now.

I have a different problem though and that is that my BD player only shows ten audio tracks (and for some reason, it shows the 1st nine and the last one). I hope this is just the player's restriction for MKV and not some general BD format restriction. I can't remember if any of my commercial BDs has more than 10 language tracks, but the most I can recall is around 8. This could be why Encore won't import more than 8 tracks. I hope not.

EDIT: I just found a commercial BD that has over 12 audio tracks, so it should be fine.

@michaeldc: There will be a nice menu and more lossless audio options on the BD, so that would be the only real difference.