On the front interior light yes there are 2 ground wires. One is grounded full time and the other goes to the door switches. For most the rear interior light is powered from the light over the drivers door and the ground is piggy backed there also.

At the tray above the light you can pull out that liner and then get to the wires feeding the light. Just make a new ground. As that wire is really undersized you could snake a new feed down to the cabinets and connect there. While LEDs do in fact use less current-power the failure mode is often a short.

Dennis