Hi Götz
you mention jumping from project to project. It’s best to align properly one “room”, then export it as a COMPONENT, room by room.
then import the COMPONENTS into a single project and have all images used in all coponents in one project…
for better orientation, use the 1+2+2 or 1+2+2+2 UI layout, and take advantage of Windows colours.
So in each 2D window have images for a particular COMPONENT/image
so you don‘t need to jump from project to project…
try it out…