In my game, I'd probably say that the searcher has a -2 dice penalty to the perception check, since it is relying only on sound, etc. But even if it succeeds, it gives no more than a general idea like "she's to my left somewhere". Basically, you just hear the scuff of a shoe or whatever, not enough to pinpoint the location of the invisible character. And the stealth roll would qualify for the Move Silently specialty (if you had it). But that is just how I'd do it...
If you don't want the fight to end, Curio could try to conjure something like magic fairly dust / glitter to attempt a Nullify on the Invisibility. But that would probably take another 10 hits to push your Conjuration to allow a magical effect. Or instead of Conjuration, maybe you can do it with Animation. Maybe animate all the dust in the room (it's an antiquities museum - of course there is dust!

), and have it swirl around, giving a Nullify Invisibility effect? Animating a volume of dust (which is not exactly a single object) might be a bit questionable, something up to the Narrator whether he'd allow it.