Found the grommets:
1. The one in the trunk lid is listed under 82 ELECTRICAL SYSTEM, 55654 TRUNK LIGHTING as PN A 317 997 02 81, 1 pc required (about $3)
2. The ones in the rear cross panel for license plate lights are in 82 ELECTRICAL SYSTEM, 001 ELECTRICAL SYSTEM as PN A 113 997 03 81, 2 pcs required (about $5 per piece)
I do not know if the position 1 comes not pre-cut these days. Not sure if it is available from MB - the system does not show the availabilities until New Year. I cannot be sure about this part, as there is no drawing in the EPC, but I do not recall any other grommet there.
Position 2 comes pre-cut - those I recently bought.
It may also be that if you order position 1 these days, you get a replacement (position 2).