Ok, after a while I figured what I want is much simpler than other solutions to similar problems in the forum. This is working for me completely.
There is a link file which contains only rooms. The solution reads from the link file the rooms and writes the number and name of the rooms to the model file. Btw the solution is running through the model file not the room file. As far as I can understand dynamo cannot write into link files.
Any way, after the room names and numbers or any parameter that can be given to the room is read, they are written to the selected model category, in my example furnitures. I’ve tried it also for floors and ceilings.
I don’t know if room height is of importance. Rooms are not 3d entities, but in sections do they have to touch the floors or ceilings or for walls do I have to change the room calculation from wall finish faces to mid cores?
I have to experiment more. Thanks to Greg and Kulkul.