Russian, Japanese keyboard entry

Hi

We have a browser based application (online surveys) written in LAMP (PHP).  We can provide User interface in pretty much any language.  However, we have heard from one client that a previous supplier's solution had "problems" for Users with Russian, Japanese keyboards. The client could not give any more detail. This is a new one on us!

Does anyone have any experience of data input problems from Russian, Japanese or any other keyboards?  What might data entry problems be and what are the solutions?

The data entry requirement is very simple.   Users either select via mouse or enter simple text responses (no mark up).

Thanks