I'm not sure specifically what 'Cap deage' means. It could be a very specific term, a misspelling, or something relatively unknown. It might be a proper name, a local term in a certain area or a very niche concept.
I don't have enough information to say exactly who Cap'n Kathy is. She could be an original character created by the fan fiction writer. Maybe she's a pirate - the 'cap'n' part could suggest that - who has some connection to the wizarding world of Harry Potter.
I don't have the precise release date of Jinx as a manhwa at hand. You might want to check reliable manga or manhwa databases for accurate information.
The update schedule for the Jinx manga can vary. You might want to check the official website or social media channels of the publisher for the most accurate and up-to-date information.