The violation, the infringement, the tortious conduct such as defamation or invasion of privacy are all the work of volunteer contributors. It is their wrong, it is their copyright infringement, it is their action, it is not the action of "us" or "we". There is no "us" or "we" in this regard.
We do have a collective responsibility however it may be expressed legally. We are working toward, and perhaps have now, established a non-profit corporation. As a corporation the usual rules apply and the corporation is responible with auxilliary responsibility with individuals who may have commited a particular transgression.
Fred