Is it necessary for employer to prepare contract in English before hire foreign person (European)?
No, even when they do, the Chinese version is the one that is legally binding.
I would recommend to any foreigner to have a local (preferably one with understanding of the law) look at the contract before signing.
Short answer: (1) no, unless the person is performing so-called blue collar work in accordance with the Employment Service Act, and (2) if so, the language of translation depends on the official language(s) of the worker’s country.
Here are some previous discussions of the topic: