As the offical CDS reference says renaming is the way you wanna see it, is not supported at the moment.
Renaming an element in a CDS entity definition is not recognized; the rename operation results in the deletion of the renamed element and the creation of a new one.
An ugly approach would be
- 1st step: create the new field
- 2nd step: copy the values from the old field to the new field
- 3rd step: remove old field
Regards,
Florian