Forumlar / Cotonti / Support / Customize quotes

I understood through a ticket in Github that it's possible to customize the quotes a bit by using resource strings in theme.php in the theme folder.

For example:

$R['forums_code_quote'] = "{\$postername}:\n{\$text}\n\n";
$R['forums_code_quote_begin'] = '';
$R['forums_code_quote_close'] = '';

I've tried this but nothing changes. Am I missing something here?