Assigning greater weighting to Chinese characters is a sensible proposal. (Many comments here are mixed Chinese/English, so it's not easy to classify which comments are in Chinese.) Shorter comments in Chinese can be semantically the same as a longer English comment. There's also an issue with exceptionally long comments in Chinese being highly obstructive. (And the same for question titles.)
It was previously proposed here: Treat Chinese character's length doubled (December 2011; +6/-0). To my knowledge, nothing changed then. It was also previously proposed at Japanese.SE: Drop minimum character limit in titles and comments (December 2016; score 14). To my knowledge, nothing changed then either.
To my knowledge, a diamond moderator cannot tweak this: it requires intervention by Stack Exchange staff. And I expect they'll say something like:
This is now less easy to bypass; perhaps one should consider populating their comment with something meaningful of 15 characters or more? Perhaps if one has less to say than that, one should keep one's thoughts to him or herself?
Jeff Atwood, 2009
Basically, there are usable workarounds, so I don't expect this to be prioritized. I did not find precedent at meta.SE of comment character limits being changed previously, and there are a lot of "no"s.
Also, if it were only implemented at Chinese.SE, it would make the limits inconsistent with other sites (currently 15 chars SE-wide) which may lead to technical issues (e.g. migration). Applying it SE-wide would be better raised at meta.SE (although I don't expect it would be received well), and maybe it should also include Japanese and Korean characters.