Unfortunately, as the link describes, Netflix only makes this available for a very limited set of languages, while everyone else is stuck with the extremely limited text-based standards.
Frankly, those text-based subtitle standards are quite maddening on their own. Netflix's text-based subtitle rendering seems to support a much wider set of TTML features than what it actually allows subtitle providers to use - so if these restrictions were to be slightly relaxed, providers could start offering better subtitles for anime immediately with no additional effort from Netflix.
Frankly, those text-based subtitle standards are quite maddening on their own. Netflix's text-based subtitle rendering seems to support a much wider set of TTML features than what it actually allows subtitle providers to use - so if these restrictions were to be slightly relaxed, providers could start offering better subtitles for anime immediately with no additional effort from Netflix.