Please note that Xilinx is JEDEC compliant and supports JEDEC compliant memory variants that conforms to the memory controller conditions that are details in UG1085 for PS DDRC and PG150 for MIG. For PS this is seen in Table 17-1 on 426 in Chapter 17. The list in the GUI's has no bearing on support but is there for customer convenience. The parts in the list are selected based on marketing decisions with regard to market trends and discussions with Micron.
So some memory device parts may not be listed or some parts may be listed that have become obsolete and have new recommended parts from Micron and this list not been updated. In this case you should use the custom part option to manually add the desired part and ensure all settings are inputted correctly by referencing the memory device datasheet and JEDEC specification.
PG201 Chapter 5 details an example using DDR3 for how to read the datasheet and populating the correct values in the PS DDR GUI. PG201 can be found in Doc Nav or at the following link.