I wondered about the comics credits so I checked the latest TPB for Batman: I Am Suicide and Finger is credited.

DID you actually watch the documentary? I feel like A LOT of this, all of these questions that you say aren't covered, are actually covered very well in old interviews that the documentarians found from both Finger and Kane and their contemporaries.

Pretty sure that they make a point in the documentary to state that Finger DID converse with his peers about taking Kane/DC to court but seeing what the creators of Superman had gone through deterred him. He told a friend/fellow creator that he couldn't afford the lawyers.