I just tested the problem here and it does still exist in the latest wrappack of NX 5.1 but it appears to already be fixed in later products like Studio 6.0 and Visual COBOL 2.3. In these products an xml status code of -9 is returned on the read instead of an RTS 114.
If you would like this to be fixed in 5.1 then please update the incident with that request and the engineer will assign a higher priority to it.