I don't have the exact name of the person who created the Omori manga at hand. It could be worth doing a search on manga databases or asking fellow manga enthusiasts for the answer.
Omori is purely fictional. The story and characters were imagined by the creators, not drawn from real-life events. It offers a fantastical and imaginative experience for players.
At the moment, there's no definite date for the Omori manga release. But you can follow the official social media accounts or manga forums for any potential news or leaks.
The impact on the fandoms is multi - faceted. In the case of the Harry Potter fandom, it can introduce new storylines and character developments that were not possible within the original series. Fans get to see how Harry would react in a completely different universe filled with superheroes. For the Avengers fandom, it adds a touch of the magical and the complex backstories of the Harry Potter world. This can attract new fans to both fandoms. It also encourages creativity as fans try to blend the different powers, cultures, and ethics of the two universes in their own works.