The actual used value that should trigger an error responsecode is currently quite deep hidden on debug loglevel. This makes debuganalyses sometimes pretty hard. And only if de API indeed throws the error message.
If the response does not contain the errormessage it is not clear what value should have triggerd it.
Perhaps it is possible to add this value to the log like:
Log error trigger value is ${value}
Even better if the reason or api specs for the specific field are added.
Log error trigger value is ${value} , accepted value is integer with max length 5