In the older 1980s Volvos (and late models too) keeping the PCV system clean and free flowing was a very common and important issue. A clogged system would build pressure in the crankcase and wreak havoc with everything from bad oil leaks to blowing so much oil into the air cleaner that it soaked the filter.

The common DIY diagnosis called for a "rattle test". You unscrewed the oil filler cap and let it rest on its opening, if it just vibrated there quietly your PCV system might be deemed clear and flowing properly. If it rattled and bounced all over, the system was clogged. I had an '86 240 that was consuming lots of oil and sprouted a few minor leaks, no smoke though. When I did the test the cap bounced around and jumped right off an otherwise smooth running engine. Sure enough the fire trap was almost totally blocked. When cleaned, everything went back to normal and the cap vibrated quietly on the cover.

I'm not saying this is it on your car, and benzes don't have a fire trap in the PCV system, but an occluded breather system would likely build pressure in the crankcase of any car and maybe enough to force oil leaks. I'm not even sure if a "rattle test" would be an indicator on a Benz, but I would think it might.
Maybe it could be something as simple as the need for a new oil filler cap (which are vented and can and do get clogged).

Note: If the filler cap is itself the problem, the rattle test would not show it.

What I'm not clear on is if a clogged breather system could have any effect on the actual oil pressure. I'm not inclined to think it would so I don't see any correlation with the increased pressure and the oil leaks (except maybe the rear seal).
One common leak that can be substantial yet hard to spot on these is the oil level sender mounted above the oil drain in the pan. The seals tend to leak as well as the unit itself through the plastic housing around the electrical connection. When they leak the oil tends to spread thin across the pan below it, running off the back of the pan and into the airstream while the car is being driven making it hard to see and determine how bad the leak is.