So the developers are already in the middle of making their next game.
Reborn Island: Cuckold Play and the Form of Love
It's an NTR-RPG. One Male protagonist, two female protagonists. One of them becomes his lover. The Dev claims that the scenario is his biggest yet and that he plans to focus more on combat compared to Amelia. The clothing system is next level too. You can customise the top and bottom outfit as well as top and bottom underwear and mix and match them as you please.
Currently, the last progress report was 27 Jun. He has finished writing the scenario and is looking for voice actors. He is also working on the actual game systems now. I think the release is planned 2025.
You can find all this info on Cien site link on page #1, post #1. Its format is like patreon. You don't have to be registered or follow to view the main progress update posts. Of course, the site is in Japanese so you will need Google translate.