I woudln't say their goals are unrealistic they're just not rly well organized, the lack of focus thing couldn't be more right tho, they posting stuff like ''we are working on making a car scene'' and it's stuff for Missy's quest that isn't even in the game yet, Mangomango doesn't have a good game design team and it shows;Honestly a very cool idea for a game, the only good games I remember having that sort of gameplay are Robolife-Days with Aino and summer memories with the calander system affecting the schedule the girls and the limited time. But I think the game is too expanisve right now to give a limited timer on, unless that time is like three years, this game would need to be compressed to fit that narrative. Especially since things like the santa events are easily missable. However events within the certain dates and time is a cool idea, hopefully it will get expanded on because right now the calander is just there to tell the date. Although it's still unlikely to happen in a timely manner unfortunately. I think the game will do something similar to what you mentioned with the 'cores' but without any major impact with the world. Many of the characters are just parodies of other people shows and media which makes it hard to make a difference without changing the theme of the world.
Unfortunately, much like many games before it, this game suffers from a lot of ambition with unrealistic goals and too many distractions. I feel like this game should have just focused on the main story first before adding more and more stuff and making more spin-offs. There are way too many side characters and events that are being added, they keep on adding things into the pot without caring about the stuff already inside of the game. It took almost a year for any update on the main story before. And although the game is much more expanisve, all the ideas are not really all that developed. This game is a cesspool of ideas and the begginnings of ideas made into one game. And I think the best thing moving forward is just to stop putting more new stuff into the game and develop whats already there. This game suffers from too wide of a vision and too little focus.
Practically all animations for the game are done already, the main ones have been done for a while now and all they need to do is actually code the stuff and somehow they manage to go with some of the most boring straightforward approaches for stuff and don't create real systems within the game, they could add special encounters like the piranha plant one, but without quests, something like:
A ghost girl haunting specific places, maybe you go somewhere and if you visit that place she starts haunting you and you can get random fights against her at night and if you lose you get a debuff for the next day or something.
Maybe a succubus that can visit you at night depending on certain conditions, like if spend like a week without fucking anyone you get visited by a succubus when you sleep and it's like a battle of attrition boss fight where she spams pin attacks to milk you dry, could make great use of the duke's blood potion to out damage her before your bar is filled.
The Slenderwoman in the park, maybe if you go there in a time where it's empty you can get attacked by her and if she beats you it's just a game over and you get booted back to your previous save point, maybe you even get a game over screen with her.
A werewolf girl that roams the city at specific nights and whenever she's out you can't use fast travel so you gotta go through the maps on foot hoping you won't find her and it's like a special bossfight that you need to either lose once or run away before you can ask someone about the means to defeat a werewolf, maybe the girl in the library.
And each of those encounters would have their own mini-systems, how they work, when they appear, what they do and what you get for beating them or losing to them, if every 1 or 2 months we got something with this level of depth while they work on the main story I wouldn't mind even if it was just one character with 2 animations because it would be stuff that builds into the game systems and make it more engaging, the way stuff work right now the characters are more of a to-do list for completionists without any real reason to engage with most side characters.
And we need a reason to explore the city past daytime since you don't really have anything to do at night other than sleep, there's like, the pervert in the park (which is great wish we had more of her), the Rapiscallion in the house and... just about it, there's also the gnome now but that's not rly that engaging, hell they could make the rapscallion girl get mad at you for always catching her and cashing in her money and have her demand you to give it back, maybe add a version of her during the day without her thief costume and make it a interactable NPC;
There's so much small stuff that could make this game legendary and would be done quite easily if they put the time to think things through, unfortunately the only real good thing this game has is the art, which carries it hard, if they paired the artist with some talented animator for the CG parts and gave their ideas to a talented creative and ambitious team we'd have the best 2d hentai game ever.