Why there's no "CFG and UFM Erase,Program,Verify" in Flash Background Mode ?
There is. However, the operations are named differently. This is for historical purposes:
Flash Programming Mode (Offline):
FLASH Erase, Program, Verify: "CFG + UFM + FR"
FLASH CFG and UFM Erase, Program, Verify: "CFG + UFM"
Flash Background Mode:
XFLASH Erase, Program, Verify: "CFG+ UFM"
XFLASH Erase, Program, Verify, Feature: "CFG + UFM + FR