It is not possible to alter that part of the message for the hardcoded messages. You can use the Add Audit Detail assertion to add customised logging. I almost always set up traps in policy to audit when something goes wrong before failing the policy. This pseudocode illustrates what I mean:
-- At least one assertion must evaluate to true // Do something else audit and fail
---- All assertions must evaluate to true // Do something
------ <assertions to do stuff>
---- All assertions must evaluate to true // Audit and fail
------ Add audit detail // Audit what just failed
------ Stop processing
Most of the time I set up an encapsulated assertion that handles that failure that includes customising the error message and other "clean failure" stuff. I can send an example if you are interested.
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Jay MacDonald - Adoption Architect - Broadcom API Management (Layer 7)
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Original Message:
Sent: 01-23-2020 10:37 AM
From: Blokhuis
Subject: Custom message in audit record