>>109512095OP here, the one who seemed to home in on older members the most was Fubuki.
Out of 15 or so chat messages that she read, none of them came from a grey name, and all of them had at least a year or two in membership duration.
My theory is as follows.
The longer you've been membered, the more likely you are to say something relevant to the topic, so she may not actually look at the badges, even if it's very coincidental.
For Fubuki in particular, she responded to messages that related to her or Cover's announced projects the most.
Closely tied are comments that are very approximate to the topic that she last talked about, e.g. she talks about yakinikuya, a member mentions their favorite dish and Fubuki resonates with it.