..the Furniture Library Editor as well as Sweet Home 3D don't try to set some default values that could correct the wrong lines...

Maybe that is even scarier, then I see my own confusion rising to even higher levels by getting strange default values. Actually, I think the perfect interface is the one you implemented with the SVG input, that it turns red when values are invalid. Just an error message could be a decent substitute (model #6 invalid... or something).

However, system works quite well as it is once you are used to it. But the real time-saver would be accessing all properties from the FurnitureLibbraryEditor (if only opening PluginFurnitureCatalog.properties as a text file - but then maybe the original file should be saved so it is possible to revert).

ok