I think in the case where the service could be down there will be an error message from the moderation API and there would be no JSON to check the profanity score, so I think in this case you can add the response received as request failed to your audit log.
For the scenario where the exception needs be differentiated, I do not see a configuration setting that could help to differentiate them based on the profanity score. I think client-side processing needs to be done to segregate the same.
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