My suggestion assumes SIMPLE_TYPE_MAP and API_TYPE_MAP are globals, exactly like API_TYPE_MAPPING is a global. Modules are only ever imported once in Python. Ever. I mean, you could go out of your way to abuse importlib to import a module twice, but I'm not worried about those people. Well, I am, but for different reasons.

Because of how Python dictionaries work (http://stackoverflow.com/questions/6605279/how-do-python-dictionary-hash-lookups-work) the typical lookup is much faster than the iteration method that exists in your code currently. That aside, for the sake of clarity alone is worth making both the table to lookup the type based on the simple name and the inverse (lookup the simple name based on the type). To give a sense of scale, we're currently talking about an extra 1048 bytes added into memory for programs that import this module.