Japanese texts are not written in alphabetical characters and thus the fullwidth parenthesis characters (U+FF08 and U+FF09) should not be handled like normal parenthesis characters (U+0028 and U+0029).
We do not usually put a white space before “（” (U+FF08) or after “）” (U+FF09) because we do not use white spaces in Japanese texts and because “（” and “）” have enough space compared to “(“ and “)”.
In the examples in the following like, the first ** are not emphasized. However, in Japanese texts, example 1 should be treated in the same style as in example 3. I understand that example 2 does not emphasize “test(test)” but it is different from example 1 for most of Japanese speakers.
commonmark.js demo )%20**%E3%83%86%E3%82%B9%E3%83%88%EF%BC%88%E3%83%86%E3%82%B9%E3%83%88%EF%BC%89**%E3%83%86%E3%82%B9%E3%83%88%0A2)%20test(test)test%0A3)%20test(test)%20test%0A
It would be appreciated if the rule for unicode punctuation and symbol characters could be revised.