I've re-classed the staircase as a teleporter and gave it a teleporter block, there is some "semi" collisions now. (It's like jumping into a wall 0.5M thick of bubble wrap) but transporting from the ground floor to the 1st floor is not that easy yet.

Interesting, Though I'm having some trouble figuring out the teleporter.

есть такая функция : Часть двери. если ее поставить всегда включено , тогда на этой детали будет выключена коллизия.

Looks like the dev's have added a teleportation item to the game. After I brought up the problem with the stairs, the dev's made a suggestion of a teleporter switch that allowed you to teleport to the next floor. I'll play around with the new item and add it to the staircases, for this one it will have (Updated) on it, and this one will become (Prop).

It seems like it gets automatically disabled when the center of the item is too far from the actual thing. If you will try to create a part which is, like, 20 blocks tall 14 of them won't have any collision. Just try to experiment with that

How do you disable the collision?

You could just disable the colision of the staircase and then put some invisible stairs blocks behind it for it to work just IF the proportions have been kept in check