I've check steemd regularly now, it shows up on there, but other than that I don't think there's a way to get notified on Steemit. Busy does have some notifications, but I don't know whether it would tell you about flagging.

I don't know what effect it has on posts older than 7 days, probably nothing, and these accounts have so little SP/VP that they just don't have any impact. Plus their list on enemies is growing day by day, I don't know how much longer they can keep this up.