so I semi-dropped the engine again and drained the oil (disconnected the oil cooler hose).
took the intake unit off...
to clear access to the air flow cover... (no more oil from the trinity-area)
then I took off the right engine tin, unscrewed the 4 nuts (2 at top, 2 at bottom) and pulled it off...
top...
bottom...
now the interesting part:
for me, at least one seal at top has failed, because you can see, that the oil spill has been sitting there for a long time already above the bottom flange...
and here are the seals (green= new)
what do you say?...