Considering nearly over a moon ago, Saburo's wife had argued with him over working excessively and taking frequent business trips, we can assume she is not part of the cult's activities nor she is aware of them.

[If that were Aymeric, Leo would have no issues dragging his overworked ass to bed and maybe cast a Gravity spell for good measure.]

As for how Lady Suijin knew about the incident in Australia, she had shown me an article in a newspaper explaining the phenomenon. Although it was more...sensational than most, it did point out the sigils which were true.