And if Marklin could also include some information about the recording, it would be great. Eg what actual motor they did record etc. take eg the G2000, Marklin has no information about the sound recording, and G200 was first delivered with a CAT 3516 and later an MTU engine. ESU states in their project that they recorded an MTU engine. since the Marklin and esu sound a bit different, my guess is that Marklin recorded the CAT engine, if they recorded an actual prototype at all??? so most likely some Marklin G2000 models that are based on the later editions have the wrong engine sound?

And take the NSB Di3 (Nohab) and Sj T44, their sound project sounds like it's the same engine sound project, but the prototypes have slightly different engines.
The T44 has an EMD 645E v12 and the Di3 has an EMD 567 v16. the prototypes sound a bit similar but there are differences.
I don't actually mind it in cases like this, but I like to know what they used as a source, as its interesting details.

and a side tip: if you are looking for extra sound effects to enrich your sound projects, something like this might be useful: https://www.boomlibrary.com/sound-effects/trains/ the downside is that it's very expensive for the limited use in decoder projects........