I exported a lob-bearing table using the SYSCS_UTIL.SYSCS_EXPORT_TABLE_LOBS_TO_EXTFILE procedure. Then I edited the export file to change the length of one of the lobs to an absurdly large number (500K). Then I ran SYSCS_UTIL.SYSCS_IMPORT_DATA_LOBS_FROM_EXTFILE. I expected this command would fail while trying to read beyond the end of the lob file. However, it succeeded.
I think that the import should fail, and the user should see an exception which identifies the line number and column number holding the corrupt lob pointer. I will attach a test case.