There is a
thread on AVS Forum that attempts to tracks this. Most Blu-ray titles that specify generic "Chinese" subtitles on the packaging seem to use the traditional character set, although Sony occasionally provides simplified characters. Fox most frequently lists their subs as Cantonese but it seems that the usage of Cantonese slang and expressions may be minimal on most Fox titles. I don't read (or speak) Chinese, however, so can't say for sure.