Currently ofTrueTypeFont
does not have full support for Unicode characters. Better international support in the openFrameworks core is in the works though. You can find our plans in the openFrameworks 1.0 roadmap see our internationalization plans here http://is.gd/of_i8n and our typographic plans here http://is.gd/of_type.
While you are waiting, the best alternatives for unicode support are probably found in the following addons: