Don't use PRSCustomize (1.04) on your reader. It doesn't support French (FW 1.3) version.
The best way for you now.
go to Sony support and download FW 1.1 US version and update to your reader (read the How to on readme) with the trick for upgrading lower version to newer version... (see on how to solve brick...)
Then you can use PRSCustomize...
or wait until newer version of PRSCustomize (1.05+)