Since the main object of the issue is to have a canonical reference to use for linking 'code object' from elsewhere in the text, I think that can be satisfied by existing _bltin-code-objects 'ref' link as Terry suggests, even though it is a bit awkward to use.  The changes to the index position are good, I think, as is having a direct index entry for 'code object'.  However, following the model laid down by 'class object', the existing index entries under object should not be lost, but instead the new 'code object' index links should be added.