My understanding of the sleek system is that your sleek won't "pop" until you're in the room or whatever, right?

So.. if you do whatever would currently make the wand spawn (be that enter the room, kill a mob, whatever), instead it marks it as the location being checked.

Sure, that might mean that you miss your wand because it spawned somewhere you didn't even realize. But that's where detect artifact would come in. I would envision it working pretty much exactly the same way as it does not.

And yes, once a location has been checked and is NOT your location, it will never be your location (unless you pick one of the edges).