You've pulled the ```_create_cf_grid_mapping()``` out of ```_create_cf_data_variable()``` for the sole reason to manage the accounting of multiple grid variable names.

This is symptomatic of  the divide between the ```SaveManager``` class and its reliance on module level functions. As suggested earlier, if you were to make the relevant module level functions methods of the class (with suitable refactoring for shared data), then the ```_create_cf_grid_mapping()``` call can exist back where is belongs, as part of the ```_create_cf_data_variable()```.