Deploy and store calculated fields using internal names
When deploying a calculated field, the formula must contain display names. It becomes problematic to use such a field if the display name of a field in a list has become different from the one in the Site Columns gallery (user rename, different language, column rename in certain lists, etc.). Besides this being more logical, the current way it works makes it impossible to deploy a calculated field for some field/list combinations. Example: the Title Field in a SP 2013 Task List has display name "Task Name", but the Title field in the Site Columns gallery has Display Name "Title".
It would be much more logical for a developer and robust when the field names in formulae are stored internally as internal names.