You did the right thing. While CPS may simply log the call, if they get enough reports over time something will eventually stick and should the parents end up in front of a judge, the record will be taken into account. I've represented parents with over 50 reported calls against them by the time they lose their kids. Each complaint points to an issue that becomes part of the case plan that must be worked before the kids are returned. The results may not be immediate, but eventually you'll see some good come from your efforts.