CYRS1545AV18 is targeting space applications and the Xilinx Kintex Ultrascale is also marketed for space applications.
The CYRS1545AV18 is limited to 250 MHz clock rate. The Xilinx Vivado Ultrascale Memory Interface Generator(MIG) for QDRII+ will not run lower than 300 MHz.
This implies that these devices are incompatible. This was a surprise to the design team.
Can Cypress provide any assistance or guidance.
I believe you are already working with the right Cypress team to address this concern.