Sorry, I saw a bed up there someplace and incorrectly assumed it was a residential lot.
With all of the sims far out of the way (MC Reset the lot if you have to), can you get a DE Radius Purge to accomplish anything on or near those two tiles? Be careful (or be prepared to quit without saving) if the Purge removes more than it should. Like the staircase, although you could put that back, or something more critical.
If that's no good, back on the MC > Object Stats, there is nothing listed that just shouldn't be like more gems or a spawner? Object Info instead of Stats should allow you to focus on certain objects like that if there aren't multiples of the exact same kind all over the lot. And does buydebug reveal anything there?