Saying there is an absence of evidence (of a leak) isn't useful by itself unless they also indicate whether that is evidence of absence (of a leak). I.e., they

Saying there is an absence of evidence (of a leak) isn't useful by itself unless they also indicate whether that is evidence of absence (of a leak). I.e., they should indicate whether it is likely that they would have caught it if a leak had occured (e.g., via extensive logging).