No, it sounds like you asked AI which is the equivalent of sending a toddler to do Google searches for you and tell you what they found.Is this true.
Under the National Rail Conditions of Travel, Greater Anglia's prosecution and revenue protection team can only recover lost revenue for their own network. They cannot calculate penalties or recover unpaid fares on behalf of Thameslink or TfL unless those operators join a joint prosecution (which rarely happens for minor ticketing audits).
That is not the situation at all. Train comapnies can and do recover losses on behalf of others. That's entirely normal given very many fares are actually split between operators.