On the other hand, it's such an obvious question that somebody must have thought about it, so I assume (stupid me) that there is nothing unsafe here. Just very expensive to repair.
The composites are made from carbon filaments and IIRC the structure also has a fine mesh bonded in to it. The carbon will conduct at the +ve here.
In the case of the D duct it looks like one of the major stikes hit a panel screw .....and welded it in! then tracked fore and aft exiting along the trailing edge of the duct.
Nothing too unsafe and yes very expensive!