In Buddhism, there is a deity called Skanda. In Chinese, his name is Wei Tuo. See for example this link https://en.wikipedia.org/wiki/Skanda_(Buddhism)
However, my question is, what is the actual correct spelling in English for the Chinese name of this Buddhist deity? Is it Wei Tuo or Weituo?
In the link, you can see that it also says that he is called "Hufa Weituo Zuntian Pusa", in which Wei and Tuo are written together as a single word.
In English, I believe Chinese names using pinyin are written together. For example, Beijing or Tu Youyou, not Bei Jing or Tu You You. This is why I wonder, what's the correct spelling here, Wei Tuo or Weituo? And why? What's the source of the grammatical rule applied to this case?