A reply I received from the man himself too people spreading misinformation in the comment section below. while he has not provided me any specifics he did at least answer my question and he is listing be patient.
Thanks for the heads up. It's understandable why they would be worried given the amount of time that's passed. Chapter 5 of Polarity is the end of Part 1 (of 2) of the story, so it's bigger than all 4 previous chapters combined. This is why it's taking a long time. Radiant Chapter 4 will actually be out first, which shouldn't be too much longer.