Okay, I don't have the book in front of me, but I'm pretty sure my memory is good enough for this question...

The Spike Pit is a tile that is placed on TOP of the bigger "Old Wall" tile from the Base game. I loved that idea! Unfortunately, it confused me a bit.

The Spike pit is surrounded by a black border. After a bit of a discussion, we took this to mean that it's surrounded by a wall, which meant that we couldn't count spaces from the Old Wall to the Spike Pit (because you can't count spaces through a wall), and abilities that work on other heroes sharing the same tile also would not work. In particular, I am referring to Astarra's ability to teleport, and Raythen's ability to allow other Heroes to use his stats to test a skill.

Was this a correct ruling?

Yes. Unless specifically stated otherwise, you can never count spaces through the black edge of a map tile. The spaces inside the spike pit are not any number of spaces away from anything outside the spike pit- they are isolated.

is there any method to push a hero to spike pit again ?

I see the rope ladder , but it seems to just need 1 time to use ,

For hero side , I feel it is almost useless.