Did you set binary => 1, which is required to use extended character sets?

No, I didn't. Partly because I didn't understand that 'binary' in Text::CSV_XS meant non-ascii characters, but then I didn't look into CSV as deeply as perhaps I might have because I thought I'd better get to grips with the XML and use a pure UTF-8 solution.

The beauty of openoffice is that it uses an open document format - I thought it was about high-time I got my head around it and made some way to understanding it. The next task is, of course, to do the same thing with gnumeric, but last time I looked the document format wasn't as well documented.