If you keep on blatantly insulting other members by calling them "kid", I'm going to give you negative ratings.
Nearly everything you said is false.
First of all, Mandarin derives from Portuguese language, and dates back to the Ming dynasty, it has nothing to do with "Manchu".
The Manchus referred to the Qing dynasty AS CHINA in the MANCHU language. They called Qing as "Dulimbai Gurun", which means Zhongguo.
Dulimbai= zhong = middle
Gurun = guo= Kingdom
The Manchus also referred to themselves as "Dulimbai Gurun i Niyalma" which translates to Zhongguoren- Chinese people.
They also referred to manchu language as a "Dulimbai Gurun i bithe" - language of Zhongguo (China).
https://webspace.utexas.edu/hl4958/perspectives/Zhao - reinventing china.pdf
They used those words in the Manchu language, while speaking among themselves.
It was the Ming dynasty who moved the capital to Beijing and started using Beijing Mandarin, which is still a Sinitic (Chinese) language, and not Manchu. The Manchus quickly adopted Beijing dialect and lost fluency in their own Manchu language after moving into Beijing.
In Vietnam, the Tran and Ho dynasty were both Chinese. Dai Viet used Classical Chinese, and not Vietnamese as its official language, all of their government systems, writings, and Confucian ideology were copied from China.