Such a topsy-turvy room could be two copies occupying the same tiles on different elevations; with the transition just being a party position switch. This would still show on the automap as being the same location.
The thing to always consider (even more than monster behavior), is that the party can drop items, and how should they behave?
(Is it really upside down or is it just the room; do dropped items fall upwards to the —floor?)
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Here is an example map that uses a combined mesh model for its topsy-turvy room. This simplifies the rotation, at the cost of immutability within the editor, as you cannot change walls of the room, except by altering the model. This model was assembled in Blender.
https://vimeo.com/357321491
https://www.dropbox.com/s/h3ellyhctjbh2 ... y.zip?dl=0
*It is possible to manually flip all of the walls as individual objects, of course...but they would have to be redefined as custom walls without minimalSaveState, because they would each lose their changes when the game is reloaded. In theory...just loop through all of the affected objects, and using the setRotationAngles(), and setOffset() methods of each model and occluder components should easily flip them 180°; that's not how it's done on this map though.