@Veseljko Thank you for the suggestion, but I don't think this is a possible solution. If the mod requires it to be on the server as well. Keep in mind this person was able to change the z value of the terrain using some type of mod. The server does not have any mods at all. So there is a solution that doesn't require installing mods on the server.

That being said If I can find out what mod was used then I probably use the same mod to fix it. The terrain looks like they used a hoe with a huge radius to create huge columns to go to the max z value of the game.