Nice work on the application

In Polish, I believe you meant "szlak" as in "szlak kolejowy" - "railway route", not "połączenie" which in my opinion is too literal. It would look better something like this:
"Czy szlak <route name> jest wolny dla pociągu nr <train no.>?" - trains without delay
"Czy szlak <route name> jest wolny dla opóźnionego pociągu nr <train no.>?" - trains with delay
"Czy mogę wysłać pociąg nr <train no.> na szlak <route name> po lewym torze?" - left track
It's not an official way to indicate trains though as you don't even need a route name for that. But for simulation purposes I reckon it's more practical to speak that way, not exactly by the book