Google Home had introduced Traditional Chinese support in Taiwan for several years. At the same time, Simplified Chinese remains in beta stages for several years. When speaking Chinese, it is not significantly different no matter if you read/understand Simplified Chinese or Traditional Chinese. Until Google Home supports Simplified Chinese, you can always add Traditional Chinese (Taiwan) in the language setting. Google Home will understand your spoken Chinese right away.
Assistant Setting > Languages
Select 中文（台灣）from the pop-up list
You may place Chinese as your primary language over your second language. At the current Google Home AI implementation, the sequence of the language will play some part in how Google Assistant responds to your routine. I will explain in more detail with examples in separate articles or perhaps with some short video to demonstrate better.
Note: Google Home app user interface (UI) changes from time to time, instead of spending time updating with picture. I prefer to provide you with steps instead so future changes in the UI won't render this article outdated.
The above works in all Google speakers i.e. Google Home, Home Mini, Nest Mini, Nest Audio, Home Max.