What I would really like is for someone to hack into Marklin's sounds and break their lock on their sound files. I have the Marklin 39241 which is a French EST locomotive that ran mostly between Paris and Basel. It has a station announcement but it is in German. I tell people that it simulates the time of the German WW II occupation but it is wearing thin. Would love to replace it with a French station announcement.
I believe other manufacturers are offering many more sound files and I think one of them has the flange sound but how would the engine know when it was appropriate to play it.
Finally someone must make a decoder with station announcements which you could play through a speaker in or under a station. A number of newer Marklin passenger car sets have decoders in them with station announcements. I have the Marklin 42790 which has a number of them and I created an Event which took advantage of them. Sadly in German. And the CS3 has station announcements and a speaker output so you could place an amplifier under the layout with a speaker and have station announcements any time. In fact you could use the real time feature of the CS3 to have scheduled announcements.

All sounds from inside, such as radio calls, can be quite unrealistic, but station calls are okay. I think M should configure certain sound functions so they can only be activated when stationary, for example station calls and leash, etc.