The deal with the USDM vs JDM Cyclone code is that in the JDM that part of the code is active since it's hardwired in the ECU, routed to the EGR pin. Cyclones don't have EGR as you know and instead uses this for the Cyclone.
On a USDM code the routine is still there but does not activate anything since the EGR pin is used for EGR. The wiring on the ECU is cut from the processors pin to the EGR and hence enabling EGR instead.
If you were to just put in a USDM ECU and run it like stock the EGR will be triggered and will be open/closing the Cyclone at the wrong time. In ECMlink you can disable the stock EGR and set the activation to 4600 RPM and use a 3 port solenoid.
Simple answer, yes you can use a USDM ECU in a JDM car. But you have to reconfigure the EGR pin properly in the ECMlink settings.
Edit: But you CANNOT use a JDM eprom ECU in a USDM car without removing the hardwired resistors and jumpers. The JDM ECU will blow your ABS pump.