A common misconception is that the ‘audit any procedure’ is a privileges auditing option associated with the privilege ‘alter
any procedure’ and thus does NOT cover the alteration of a procedure that is
owned by the user altering it.
Note that AUDIT PROCEDURE covers:
CREATE PACKAGE BODY
Also Object Auditing Options ‘ALTER’ does not apply to Procedure, Function, Package, so
even object auditing can’t cover this.
I think otherwise every implicit recompilation would trigger an undesired audit record.
There’s no corresponding Statement auditing option available for ALTER PROCEDURE
it looks like this was not implemented for some reason.