I have tested with different locales with codepages including above. There are few which return different locale code but the error messages in both the cases are the same. I have attached the test and log files.
But there was one case, where locale code and error messages both are different.
Portuguese_Brazil.1252
log from [1] 2020-04-28 14:27:39.785 GMT [2284] DEBUG: IsoLocaleName() executed; locale: "pt" 2020-04-28 14:27:39.787 GMT [2284] ERROR: division by zero 2020-04-28 14:27:39.787 GMT [2284] STATEMENT: Select 1/0;
log from [2] 2020-04-28 14:36:20.666 GMT [14608] DEBUG: IsoLocaleName() executed; locale: "pt_BR" 2020-04-28 14:36:20.673 GMT [14608] ERRO: divisão por zero 2020-04-28 14:36:20.673 GMT [14608] COMANDO: Select 1/0;
AFAICT, the good result is coming from the new logic.