It's just a lot of assuming really and overall none of this is worth overthinking, I understand threads like this can be made due to the frustration of not being able to be in the outskirts as a high OCR character, but presuming this and that doesn't add anything or help solve the big mystery.
If I were to use the process of elimination I would consider the likelihood of some invisible mage using mass see invis and Radu happened to be in the range, because people buff behind that house all the time. At the end of the day no serious issue happened and if the staff wants to make a new rule clarification they can, that's S+.