[X] They could wait outside the town, and have Naja go in and send a message for Karle. This would be the most discreet, but might take some time until he arrives. Then, it's a matter of whether he'll go to meet her or not.
[X] They could journey into the ruins to meet him. It would be faster, and in some ways more private… but there would be the risk of assistants or other explorers being around to see Lotte, unlike with having Lotte wait out of the way for Karle to be led to her.