In this situation, can you park the car on the right side, on the sidewalk immediately in front of the railway crossing?

Why?

No, the location immediately before the crossing is within the section where parking is prohibited, between the visible single-stripe marker and the crossing. The prohibition applies on both sides of the road, including the pavement. Leaving room for pedestrians or seeing another parked car does not make parking there permissible.

art. 49 ust. 2 pkt 3 Prawa o ruchu drogowym