I also found a thread almost identical to my issue:
https://z22se.co.uk/threads/po-341.13766/
In regard to your questions, after returning the "good" coil pack to the 2005, everything got back to normal, the car works fine and the light will not light again.
I also tried installing the "Original faulty part GM P/N 12580537" again to its original car, the model 2008 , the original fault is coming back after it heats up with serious misfiring (car shaking and runs slowly almost choking).
I also tried to mix sub parts in the original faulty part, I tried the install the original base part (black color) but replaced the rubbers and the mini computer from the Ebay part, but no success. I also got another Chinese part from Ebay (before I new it would not help)...
The car from 2005 I have from the beginning and I am sure it is a genuine part which came with the car from the factory, in regard to the model 2008, I don't know it's history but I noticed that its P/N marking was engraved , don't know if that means anything but maybe its newer Firmware version?
Meanwhile I will order from Ebay another used Delphi original Coil Pack to see if it helps.
Many thanks for all your help guys!