There is a module in xlrd for reading formulas (https://github.com/python-excel/xlrd/blob/master/xlrd/formula.py). I am not sure how complete it is though (the two main functions both say they are under construction). Ideally, the formula would come in parsed into a tree of function calls and references.

My interest is in providing on-the-fly translation from a sheet in an Excel document to a Mimi model component, so non-technical users have a way to make changes to certain components.