Thank you for sharing this! Sorry to hear you hit these bugs - they are known to us. I’m not sure whether we will update the game, but if we do, they are in our bugs list to investigate!
For the ending, you are correct that it should not stay black! There are two possible ending scene sequences, depending on whether or not you collected vessels before abilities. Not sure which you saw, but neither should be black. I’m so glad you got to see one at least!
Thanks again for reporting back!