Structured content doesn't apply lang=ja

[toasted-nutbread]

⚠The current version of Yomichan seems to apply lang="ja" attributes to standard glosses which contain Japanese characters, but not to structured content glosses. By default, most browsers will render the characters "直次茶冷" in simplified Chinese.

Out of scope for this PR, but this may be something that's worth updating at some point also, since this seems like an oversight on my part. (not saying this is something you should do)

Originally posted by @toasted-nutbread in #2129 (comment)