I believe there may be some changes in the syntax that HP's opcmsg expects in our installed version (7.2) and what this module is programmed to provide. Would that be a correct assessment?

Maybe. I know nothing about this thing, but I see the error comes from

ok( 0
   ,opcmsg( OPC_SEV_MINOR
          ,$application
          ,$object 
          ,"this is ia test of a perl XS implementation of opcmsg (tes
+t 2)" 
          ,$msg_group 
          ,$ENV{'HOSTNAME'} 
          )
); #10
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Its a safe bet $ENV{HOSTNAME} is defined and "correct", but what about $application, $object, $msg_group?

my $msg_group = defined $ENV{'OVO_MSG_GROUP'} ? $ENV{'OVO_MSG_GROUP'} 
+: 'OVO_test_group' ;
my $application = defined $ENV{'OVO_APPLICATION'} ? $ENV{'OVO_APPLICAT
+ION'} : 'application' ;
my $object = defined $ENV{'OVO_OBJECT'} ? $ENV{'OVO_OBJECT'} : 'object
+' ;
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