here you go, from Xinhua:Here is the section of wiki that you referred to.
The official English-language
Here is note 2
So who used the term "president" when and where? The statement only referred to note 2. Neither of them give a reference of China used the term "president" in formal correspondence.
Remember wiki is nothing until it quotes a verifiable official source, such as the English version of a treaty or agreement in which Xi Jinping signed his name under the word "President of People's Republic of China". I am willing to wait and see for that.
The bottom line is that, only the Chinese name is the official name. Rendition in any other language is just a word that anybody such as journalist may choose at will except if it is on a paper of legal status. For example, Soviet Premier were translated to either "Premier" or "President of the console of ministers" in English, which is official? And who decides?
don't tell me Xinhua is not crediable enough and boao forum is not official