I'm from a country where for the web-access usually the iso-8859-2 charset is being used. Unfortunately, the solution in
NoWarningWhenEnteringNonStdChars doesn't work, because the charset is already specified in :
HTTP header (CGI.pm module)
template files (already contain META tag)
I would propose to:
Remove meta tags from template files that add the default us-ascii charset
Use the CGI.pm functionality to set the default charset according to some configuration option