I've retested your original file.
The bad news:
It's difficult to make different library for different projects.
What could be good for one could be wrong for other.
In all the cases you will have a limited range of good view in SH3D plan view.

The good news:
If you print the plan as pdf you will have a correct view.
Let the program to choose the Best fit scale at first attempt.
In this way you could keep your 1mm thickness lines.

To use some colors it is a good idea but depend on who look at them.
You could add a legend with explanations to the plan.

PS I have to thank you because of you I've was forced to update the creation script. [:)]