1. Varieties in Chinese
Simplified Chinese vs. Traditional Chinese: These two are written systems of Chinese. Simplified Chinese is mainly used in mainland of China (zh-CH) and Singapore (zh-SG), while Traditional Chinese is mainly used in Taiwan (zh-TW), Hongkong (zh-HK) and other countries. They are totally different in character sets used, and quite different in terms of style, terminology, punctuations, etc.

Mandarin vs. Cantonese: These are two oral systems of Chinese. Mandarin is the official spoken language in the whole mainland of China and Taiwan although there are still MANY other dialects spoken in different areas, e.g. Wu in Shanghai, Hakka in Fujian and Taiwan, Mongolian in Inner Mongolia, etc. Cantonese is popularly spoken by people in Hongkong, Macao and Guangdong province of China. Mandarin and Cantonese are usually mentioned when voiceover needed.

2. How to improve your Japanese translation quality?
(1) There is a huge difference in grammar and semantics for English, European language and Japanese language.
Besides grammar rules are widely different with totally different order of Verb, adjectives and Objects, there is also the ending statement which can be normal or polite form or very polite form. And depending on context, the consistency of ending a statement may need to be kept for some uniformity. In other words, Japanese language has a lot more variations of sentence construction and requirements. That is also one of the reasons why Japanese client reviewers are not easy to please as well.

(2) Each Japanese sentence mostly consists of 3 writing scripts.
Hiragana (for grammar related, verb for some context), Katakana (for foreign English object terms that do not have equivalent Japanese translated terms) and Kanji (similar to Chinese characters and used for Subjects, verb). Depending on the target audience in Japan market, the client reviewers' demographical background, newer generation can accept more Katakana while older generation may prefer more Kanji for familiarity.

(3) Unique Japan competitive environment
One more reason why Japanese market is unique for translation, there are many well-known domestic brands and these home-grown strong brand writes their materials from Japanese language itself while international brands translate their materials and websites. Comparing home-grown brand materials and international brand materials, most sales and marketing folks in Japan would require their USA or European HQ to provide near-to-domestic brand written quality to show the real authenticity when competing with them. This is real sharing from my international clients of their challenges with Japan market localization.

So, to ensure the project a success, it’s very important to discuss with Japanese reviews and/or end-users about their specific requirements regarding style, terms, how they want the legacy materials be used, what the format they want to review, etc. then develop Japanese styleguide, glossary and instructions to linguists, before the translation process starts.