The original instruction you posted about was an SSV to read the FaultCode attribute of the Module Object for the 22-COMM-E itself. This is an error code related to the logical state of the CIP connection between the Ethernet module of the controller and the 22-COMM-E.
As you have seen, it is not the same as the actual drive Fault code. Those are Parameters you need to read from the drive.
There are examples of how to address the various drive Parameters in Single Drive and Multi-Drive mode in the 22-COMM-E User Manual.
The MSG instruction target is still the 22-COMM-E. The Parameter Number is what determines which drive and which parameter in that drive will be read.
The table I always return to is on page 7-20 of Publication 22COMM-UM004, where it shows the offset that you have to add to access the 22-COMM-E itself, or Drive 0, Drive 1, Drive 2, Drive 3, or Drive 4 in Multi-Drive Mode.
To read the first Fault code in the drive, you want to read Parameter d007.
For the PowerFlex 40 (Drive 0), that will be Instance number 17447 + 7 = 17454.
For the PowerFlex 4 (Drive 1), that will be Instance Number 18471 + 7 = 18478.