You can use Chinese, Korean, and Japanese text in iBooks Author, but there are a few limitations to books using these languages:

• iBooks Author does not support right-to-left text editing.
• iBooks Author does not support vertical text editing.
• iBooks Author does not support phonetic symbols, such as ruby or bopomofo.
• iBooks Author does not support nonstandard characters, such as gaiji.
• Books using Chinese or Japanese as the primary language cannot be published to the iBooks Store.
  Note: You can still export your book for distribution in other channels, but please review the limitations on distributing books exported to the .ibooks format outside the iBooks Store.