I'm not 100% familiar with Polish environment, however, I believe the brakes operate the same way as in the rest of Europe.
It is far far away from reality, if you release the train brake and "2 seconds" later, 3000t 600m freight train is completely released. With such response, it is very likely an arcade game rather then a simulator.
I understand it is not easy to simulate that, however, it can be done (e.g. ORTS CZ/SK https://msts-rw.cz/openrails-icik-cz-sk-verzia/ ). If different levels of difficulty is required, I'm ok with that, but for realistic simulation it is necessary to include brakes model in the simulation.