I entered this as a bug instead of a support request. I'm not sure which is appropriate. Please see https://sourceforge.net/p/kdiff3/bugs/198/. In short, version 0.9.98 of KDiff3 is apparently misreading the Chinese string 請稍待 as 請稊待 in the input files, which causes it to also change the content in the output where no change should exist. Version 0.9.96a did not do this.