1. Why you've installed under /opt which is under root system?
2. Why you run it as root?
2.1 This is not recommended to do for any applications which usually have to run by a user!
2.2 Particularly for SH3D is that will create the .eteks properties folder under root and not under /home/[user-name]/ if you run it as root.
3. I don't know from where you have "SweetHome3D123" file and what is inside. It should be only "SweetHome3D".
4. There have to be also "SweetHome3D-Java3D-1_5_2" file.
Try to run with this file.
5. If you follow STRICTLY the steps described in user's guide this files need to start SH3D by double click on them.