When I run
select calendar_since(created) from dba_objects where rownum <= 2;
I get this result
CALENDAR_SINCE(CREATED)
--------------------------------------------------------------------------
Message 7 not found; No message file for product=RDBMS, facility=HCSC
Message 7 not found; No message file for product=RDBMS, facility=HCSC
It looks like something is missing in the installation of the Oracle AI Database 23.26.1.0.0. I get the same result in the Autonomous Database with version 23.26.1.1.0.