There is a statement from the Secretary of the Pope Emeritus. I would go with his statement. Any call for Pope Francis to resign is premature.
There is speculation that Pope Benedict XVI resigned in order that a person more able than he could manage the various scandals, including clericalism, facing the Church.
While the letter to the pope is written by an individual who in the past had a reputation for finding corruption, there are also supposed personal differences and biases. Much of the letter, as the Pope Emeritus iterates, lacks a factual basis and evidence.
Furthermore, Pope Francis has been open in the past to delegating some of his authority, which would help with legal proceedings that can be handled on a more local/national basis. The USCB has asked for an audience. I am not sure whether or not they are including the recommendation of a lay board. This may very well go against the interests of some traditionalists calling for Pope Francis to resign. They would prefer to keep the status quo even if there may be a better way of getting to the truth.
One abuse victim has openly commended the United States for being the only country for having recourse for victims. My personal opinion is that has to do with our unique judicial system.
As another poster has already stated, scripture says two or three witnesses are needed. Pope Emeritus Benedict XVI has already refuted the statement.