The grouperLoaderLdapErrorUnresolvable option doesn't seem to have any affect. Remove it.
Add option in the loader properties (i.e. globally for all loader jobs) to specify how to deal with unresolvable subjects. If for a given loader job, there are more than a specified number of unresolvable subjects, the result should be SUBJECT_PROBLEMS. If less, SUCCESS.
If running the loader via GSH, print out the unresolvable subjects. Make sure it's also being logged to the file.
Improvement
Minor