There are too many ways to author a DVD with subtitles for the same conversion options to work correctly every time, especially on discs with “translation” subtitles. Some, like Dances with Wolves, have a separate subpicture stream for the translation, so the “Forced Only” checkbox is ineffective. In others, like DaVinci Code, the French and Latin translations are part of the English subpicture stream and the checkbox for Forced Only works perfectly. And these are only two of the most common methods you’ll find. The best answer I guess is to experiment using short conversions (1 or 2 chapters) that have both regular subtitles and translations and see which settings produce the correct results. You can download jeanl’s free and excellent DVDSubEdit for exploring and modifying the subs in all DVDs. Works faster if you rip the disc to a HDD folder first.