I have few suggestions @Puybaret:
1.Folder with THIRDPARTY-LICENSE files
2./lib/Furniture.jar #modified Default Furniture
I rearange with Library Furniture Editor and rewrite the catalog.
3.Modify menu text
/lib/SweetHome3D.jar:
com/eteks/sweethome3d/swing/package.properties:
-line 1020 Show selected level #in place of Make level viewable
-line 1027 Hide selected level #in place of Make level unviewable
I hope to not offend anybody.