What exactly he doing? I mean “invest on long term distance” is what? He rewritten scripts? Redraw arts? Change game engine?
It started as an art overhaul, eventually encompassing the re-writing of scripts and other code to facilitate the art changes. An update to the engine (This game uses the RPGMaker version from 8 years ago; there has been one release since then and a recently announced RPGMaker-Unity engine integration) has been brought up before by patrons and discord users, but it has fallen on deaf ears.
You can see proof of the art overhaul in game. There are still assets present in the old art style that Mulan has mentioned that they plan to redo (the two other roommates primarily, there was a bimbo event as well, MosFilm is still implemented in the old art style, etc.). This recent update just finished the framework for the Kira art update. Mulan is still going to have to go back and update a sizeable amount of the old events to support the new Kira art. 11 breast sizes, 3 lip sizes, 3 thigh sizes, a bunch of hairstyles, body-writing, tattoos, piercings... Not all of the old events need this stuff, but there are events, such as the roommate party event, that are not tied to a specific point in the story so theoretically all of the body-mods need to be available in the event. The promise of new content in the coming updates just delays this from happening.
I feel like a lot of people here either don't remember or weren't around to know why the full art overhaul was necessary. It has definitely been mishandled, in how many times things have failed to be finalized and how much say the patrons have been given over the depth of the art, but it wasn't some random whim that the dev had to just change all of the game's art.