I'm sorry, I can't offer any advice, but I do have questions, could somebody more learned than me shed some light on these points?
What are we actually seeing here,
ie. How is it possible for the coil current to still be 6A after the PCM has removed ground path. I assume this from what is being shown in CHA, after the 1.2ms time to saturate the line rises to 12v again?
I'm not at all familiar with the setup, and have never delved much into the reams of coils with more than a simple power and ground circuit. I'm aware some can be triggered on a 3rd wire, and even have a forth wire for a feedback of succesful spark (thinking about COP here). I realise a DIS on wasted spark would have a common power lead, and 2 switched negatives.
So, coming back to this case, if on CHA the ground return has been removed, why does it not induce a spark? We see that the ground path is completed to charge the coil, then it appears that the PCM drops the path, surely that should induce a flux collapse there and then?