We have made some fixes to ODPI in oder to support TimesTen and we will shortly be announcing support for Python and Node.js using the Oracle ODPI based drivers. In the future we also plan to support Go via ODPI as well. Keep an eye on our GitHub repository (https://github.com/oracle/oracle-timesten-samples) for the latest support.
Having said that, the current ODPI based golang driver has been shown to work okay with TimesTen so maybe you have some configuration or environmental issue. Can you provide some details of your setup, environment, tnsnqmes.ora file contents etc.