Yes, that would be the seal that is most likely leaking according to these specific photos. It's about $10 or so in cost & very easy to replace.

Keep in mind that this leak may not be the root cause for the codes & seeming EGR issues you've experienced. Also, the air leak could be between the anti-shudder valve & EGR Valve, as well as between the EGR Valve & Intake Manifold; all of these have been reported as potential leak points that have caused codes to be thrown.

Open your oil filler cap with the engine at idle... There is a lot of stuff that gets aerosolized / misted in the crankcase which you'll see wafting up thru the oil filler neck if you take the cap off, as well as hearing a noticeable repetitive "tock" sound from the vacuum generator / pump. Diesels are a pretty violent engine; hence why they're built stronger, & why they're regarded as longer lasting IF well maintained

With post inject DPF regen systems (as is the case with the M57), you'll get higher quantities of unburnt diesel misted into the air in the crankcase, as well as normal & expected combustion blow-by & misted engine oil... The CCV system isn't 100% efficient at filtering all of these things out of the air stream from the crankcase that gets fed back into your engine intake between the MAF Sensor & Large Turbo Air Intake, to be (re)burned in the cylinders... If you have any leak points post turbo charger in your intake system, this oily substance will gradually buildup near the leak point. Diesel fuel does not readily evaporate like gasoline, so it contributes to the oily substance & mess left on surfaces, where environmental dust & other debris will stick to the wet oily substance...

The misted / atomized diesel fuel & engine oil that gets fed back into the air intake system isn't that big of a concern in my opinion by itself, & possibly serves a lubricating function on the EGR Valve & intake valves; however, where this closed loop CCV system becomes a concern & downfall is that burning this misted / aerosolized engine oil in the cylinder causes higher quantities of ash to be sent to the DPF than would otherwise be the case if it were simply unburned diesel fuel & combustion blow-by (hence why DPF equipped Diesel engines spec out low or mid sulfated ash engine oil (low or mid SAPS)...

The primary reported issue w/ a closed loop CCV system in a modern diesel engine is due to the introduction of soot from the EGR system, where the aerosolized engine oil, diesel fuel, & combustion blow-by, is mixed & combined with soot & ash particulates from post combustion exhaust gasses, creating a slurry that is similar in consistency to tar / asphalt... When this engine oil / diesel fuel / soot / ash mixture builds up inside the engine intake system, it's called CBU (Carbon Build Up), which can & will cause issues with the function of the engine in a variety of ways.