There are two Japanese issues users are experiencing, the first is that if you type text in full size katakana and then try to insert a space, nothing happens until the text is repainted, i.e. you select the text where you expect the space to appear. All the spaces you typed will then appear.
Secondly, and I don't know if there is anything that can be done about this, if you copy Japanese text from a WPRichText memo and paste it into word, the encoding is not brought over and you get garbage mojibake. However, if you do a Paste Special in Word and choose "Unformatted Text" or "Unformatted Unicode Text" it does come over OK.
There is a third issue that I haven't actually been able to repeat yet (probably because I don't know how to type Japanese) but one that someone may recognise is that the Japanese users showed typing Japanese text on a line. The line began with katakana and ended with hiragana and some characters were invisible until the user hit Enter, there was a space where they were expected.
These problems also occur on the MultiDemo exe, which I think means it affects WPTools 6 as well. This is on Delphi 7 and WPTools 5.51.