I don't have a definite answer for you on when the after-ending will come. It could take a while as they need to ensure the quality and coherence of the story.
The normal ending in Mystic Messenger can't be simply considered the true story. It's more like one of the many storylines the game presents. Different players might have different views on which ending feels truer to them based on their experiences and choices within the game.
The Visual Novel Mode in Mystic Messenger is a gameplay style that presents the story through static images and text, allowing you to make choices that affect the outcome.