From the information I have read about this module, it looks to me that this functionality is no longer needed, or at the least not a normal requirement.

I would suggest that this be entirely removed from the code base, since the functionality has been updated to retrieve custom fields directly from SalesForce. Or at the least (in case it is needed for backwards compatiblity), hide or collapse the Custom Field Editor.

My typical workflow is to create the Custom Field in SalesForce, go into my webform, add the field, the SalesForceField Key is automatically populated with the Custom Field I added in SalesForce, pick the new field, and move on to the next one.

On the other hand I just started using this so I have no idea if people are still using this functionality for specific purposes.

Just a suggestion, trying to reduce the complexity of the code, to reduce fail points.