Should Chinese text be grid aligned in game dialogs?
In general, we don't care if it is grid aligned or not. And even in fonts that are not fixed-width, the Chinese characters usually have the same width.

To make it to look better, it is better to make the right boundary a straight line, not zigzaged. If you find it hard to achieve, then just leave it as it is.

Some punctuation marks, such as commas (，), periods (。), question marks (？), etc. do not appear at the beginning of a sentence, and can stick out of the right boundary.

In Chinese, we use full-width punctuation, not the half-width counterpart. And we don't include spaces in sentences. If English is mixed in the text, half-width spaces are usually used to separate English words (not between English word and Chinese characters).

Edit:

In Microsoft Word, there is a list of punctuation that should not start line:

!%),.:;&gt;?]}¢¨°·ˇˉ―‖’”…‰′″›℃∶、。〃〉》」』】〕〗〞︶︺︾﹀﹄﹚﹜﹞！＂％＇），．：；？］｀｜｝～￠


And there is also a list punctuations that should not end a line:

$([{£¥·‘“〈《「『【〔〖〝﹙﹛﹝＄（．［｛￡￥