Hi Saravan,
I just tried the "non-existent logon language case", but that must have been a "bug" in an earlier release. With the current patch level it works ok and I get can see in the errorInfo struct the standard error message coming from R/3:
errorInfo.code = RFC_LOGON_FAILURE
errorInfo.message = "Select one of the installed languages"
Will try the "no-authorization case" later. But in any case, if you know more examples of unclear error messages, please note them here, so they can be improved.
Best Regards, Ulrich