"Imaginably correct as of the moment I landed on the Worldwound, but since then I've been teaching you in particular and also I plausibly landed on somebody who'd understand me better than other liars -"
Wait. Has he been distracted enough by considering whether that particular response sounded less like Carissa than the previous ones, wondering if they read his mind and brought in a different actor to run that, that he's failed to consider the simpler possibility where the person he tickled was not Carissa at all -
A thought crosses Keltham's mind, and he quickly reaches out and grabs the hand of the possible actor playing Carissa Sevar, before they could be invisibly spirited away and replaced.
And Keltham considers whether to use up his one Glimpse of Beyond to check on the true identity of the person whose hand he's holding.