This mod will allow you to move simple structures within Minecraft 1.12.2 (Forge) from one coordinate to another with a smooth transition by using a command.
The mod does not add any new blocks and only contains the moving feature executed by command.

Syntax:

The syntax of the command is /sm <x1> <y1> <z1> <x2> <y2> <z2> <xOffset> <yOffset> <zOffset> <ticks>

The structure that you want to move should be within the area of x1/y1/z1 and x2/y2/z2.

The Offset values define in which direction the structure should move e.g. "0 10 -1" would mean that the structure will move 10 blocks up and 1 in negative z.

Ticks is the time in tick (20 ticks per second) to make the movement.

Basic Example
You have a structure between -100 20 4000 and -150 120 3800
You want the structure to move 10 blocks positive x and -15 blocks negative y. The z asis shouldn't be affected and the whole animation should take 5 seconds:
5 seconds = 100 ticks

/sm -100 20 4000 -150 120 3800 10 -15 0 100

Limitations?
The mod can only move simple structures. That means any NBT data in the block is likely to get lost once the movement is done. Blocks like doors, itemframes or signs usually don't work or at least get set to their default. It also doesn't work with colored stained glass Aswell as some other semi-transparent blocks. Blocks won't be connected while moving. So a "castle gate" made out of fences will look like a bunch of poles instead of a grid. Only for the duration of the movement of course.
This is also not going to be fixed in the future!

Why does this mod exist?
I've ordered this mod on Fiverr 3 years ago for a Minecraft Project. It was custom made for the project which was a realistic recreation of the Broadway musical "The Lion King". And I needed a modification that allowed me to move the set (including curtains for the theatre) on all axes smoothly. That's what this mod is for.
I've always kept the mod secret since it was a unique part of the project but now since time has passed I thought it might be worth sharing, at least for those who create similar projects. I did not code this mod myself but commissioned it and own all rights. The original mod author was called "mawathilde" on Fiverr.

I hope you can still use this modification for your project.

Structure Mover