Language files which contain non-ascii characters should either be properly
marked unicode files (UTF-8 with a leading Byte Order Mark or UTF-16 with a
leading Byte Order Mark) or should encode those characters as \u escape
sequences so that they are usable on systems where the default C-String
encoding is not the same as the one on which the language files were created!

Since it is generally not easy to edit unicode directly, or enter the
correct unicode escape sequences, it is recommended that you use the
cvtenc tool to perform conversions of the files before and after editing
in the default encoding used by your system.

For example, to edit the French language file so that it contains an ascii
propertly list with \u escape sequeneces, you could do -

cvtenc -EscapeIn yes French > tmpfile
vi tmpfile
cvtenc -EscapeOut yes tmpfile > French
rm tmpfile

A common case is where you have a file in UTF-8, but the Byte Order Mark is
missing, so you need to fix it up ...

cvtenc -Encoding 'UNICODE UTF-8' FileWithMissingBOM >tmpFile
cvtenc -EscapeOut yes tmpFile > French