Do you still need help on this?
I believe proof reading is necessary.
Actually I have some experience of proof reading of survey questionnaire but it was awful and needed to build again from the scratch.
That happens quite often when someone translate into Japanese, especially when translator is not native Japanese speaker.
I cannot commit to complete it all yet since I have not read either your original book or translation, but I'm interested in your book.
I'm not a Tableau expert but have some experience and sure I can refer to Tableau help in Japanese.
How can we start conversation?