So, there exists no rule, that says that "the track having entry signals must be tagged with usage=*" and yet you say that it is a must based on exemplary graphic... Mhm. Sorry, but this is not a rule which has been agreed on, but only your interpretation. The only things stated on this page are:

* The key usage=* is used to identify the primary usage of a railway track
* Inside a railway station area, use usage=main or usage=branch only for the main tracks (not for siding, yard tracks etc.)

It may be true for German railways (Still there are non-compliant examples in DE as well, but hush hush), but it doesn't imply automatically that in other countries it is 1:1, given how different regulations and classification is. So the only thing I have to say is to follow the other countries tagging schemes, not reflecting the German one

That is not true. Nowhere on that page there is stated clearly that "Tagging tracks which don't leave the station with usage=main/branch violates the tagging principles which has been agreed on". Unless you want to show us exactly where is that line suggesting the above.

FYI a single comment in discussion page is not a proof since it's not documented and doesn't correspond with the up to date wiki page (being there's not a clear consensus in that matter).

I'd like to know then, where those tagging principles are written as well, since it's the first time I'm hearing this

Nie wykluczam, że na terenie Stacji Obsługi to właśnie MPK jest zarządcą. Miałem się za to zabrać, więc jutro lub w weekend to zmienię (wraz z numeracją torów)

Hi there, wouldn't it be necessary to connect this railway=ferry route to the nearest track in Ystad? It would allow to show the continuity of the route.

Maybe another route, only as railway related?