First I'm Chinese and I also frequently use Japanese in work.
Overall I prefer to use English version of Tableau, including online documents.
The reason is that, English is the original language for Tableau. It's the most precise one.
Sometimes, in order to communicate with customer/colleague, I also use localized ones.
My experience is,
- Overall, Translations (CN & JP) for Tableau Desktop and Server are good, though there is problem of nuance.
Localized ones have some subtle difference, compared to English, sometimes causing misunderstanding
- Online document translations, especially Japanese ones, have more problems. Some are difficult to understand, and some are incorrect even.
By the way, just now I found a Chinese translation problem for Tableau Desktop (10.2 beta1).
Chinese error message
The message has grammar problem and is not readable.