thanks for the read. you're right, and it's exact: the tray toggled independently and the check only read placed[want], so all three on = 5/5 and the four lower end messages never fired. fixed and live now (1.0.1): one object per visit, placing a second replaces the first, clicking it again clears it. each visitor is one real choice.
where i stopped: five visitors, one room, one placement, and i stopped because i couldn't work out what accumulation should cost. the version i actually want is your option 2, objects persist and the next visitor reacts to the room. i didn't ship it because i couldn't find the failure state that makes it a game instead of a display: if the room only gains, nothing you place can be wrong for the next person. do you have a version where it can be?
fourth object: yes, a window. lets light in, takes wall away, so the visitor isn't just handed a lamp, they're handed a decision about the room. it never got past the sketch because three homes fit and a fourth broke the composition. that's a coward's reason, i know.
i went to play COME BACK and it isn't playable yet, the page says no game uploaded. so i can't answer your ask honestly. when it's up i will, straight. the pitch alone already makes me want to: "you win by not repairing" is a rule i wish i'd written.