When the game have Chinese traditional subtitle?
We don’t know.
I’m afraid there is a possibility that we never get more than 5 languages for the game
Aren’t the games localised? It’s not uncommon for films and games to only have subtitles for that region.
For now we have what we have.
Many of us believe that additional languages support will be added sometime after launch, but since it wasn’t confirmed by the developers, the chance is ghostly.
Only hope is there
Looking at some Chinese H3 and Korean H2 videos, everything seems to either be in English, or English + creator subs? 
There’s full Japanese support in H1 & H2.