The PCF8574 part is only the fzp file (one of the 5 files that makes up an fzpz file) and the usb2lcd1602-3.fzz file doesn’t have a PCF8574 in it. If you have the original .fzz file that isn’t working I can probably tell you why though if usb2lcd1602-3.fzz is the original file the lack of the PCF8574 would be the problem.
Peter