Wrong Default Encoding!
Imho you chose a wrong default-Encoding for your Parser. I know that the creoleparser-Module chose utf-8 as default-Encoding (which sucks!), but Jinja2 requires Unicode. So I would propose to modify the creation of your Parser object as follows:
self.creole = Parser(dialect=self.dialect, method=parser_method, encoding=None) }}} This way the encoding-Argument is passed to the creoleparser Module and enables one to pass Unicode to the parser and to retrieve Unicode as return value. That ist so important in order to work porperly with Jinja2.