You might be able to assure her you are interested but can only really test for ingress when/after an event happens. You can then arrange a thermo guy come and test on-site, but, this needs to be done within a day of so of the rain event or the ingressed moisture evaporates and it shows nothing. That way if she has genuine issue you have independent advice that one exists. It’s just a guy with a heat/moisture sensing camera who does a report with pics of what hes seen so not that dear. Alternately, maybe let her arrange for this or something that she will pay for if there is no issue, and you will reimburse if there is.