I can respond to that.
Informally is a bit of a misnomer, because it can be informal without the utilization of various redress mechanisms, or it can be informal at the end of a process of using redress mechanisms. For example, in one of the cases I was involved with, at the end of a protracted process of trying to resolve it, with grievances having been filed and with investigations and so on and so forth, a settlement offer was proposed and subsequently agreed to.
It's informal in the sense that normally some of the agreements are considered confidential, so they're not precedent setting, they're not publicized, and they provide no information to the larger body of workers about a sexual harassment file having been dealt with in x way. In that sense it's informal.