A lot of people in that sub Reddit have researched the church's history. Maybe the way to go is to post a question there and see if anybody can get you a source

A lot of people in that sub Reddit have researched the church's history. Maybe the way to go is to post a question there and see if anybody can get you a source in support of the claim, or a source that refutes the claim. No need to redo legwork that's already been done.