Japan certainly adapted kanji to fit the Japanese language, but I was not aware of a dispute about the origin of the characters.
Obviously they have diverged; Japan has made efforts to simplify kanji forms, although not to the extent of zh-cn, unless you count hiragana and katakana, which are derived from kanji:
> Japanese "Chinese" readings have more in common with the Chinese spoken at the time than modern Chinese.
Yup. There are even names for the various readings based on which era/dynasty they were borrowed during. E.g. for the readings of 明, "myo" was borrowed first, then "mei" a few centuries later, then "min" most recently.
Obviously they have diverged; Japan has made efforts to simplify kanji forms, although not to the extent of zh-cn, unless you count hiragana and katakana, which are derived from kanji:
https://upload.wikimedia.org/wikipedia/commons/7/7a/Hiragana...
As a side note, I was taught that Japanese "Chinese" readings have more in common with the Chinese spoken at the time than modern Chinese.