I agree, and I am an enthusiast of rpgm games since in a porn game I enjoy the "game" part as much as the porn, this game have no reason for use rpgm engine since it does not use the rpgm features for anything, making this game in a renpy engine would make it have a lot less of unnecessary grind and be much less buggy.No offense, but games like these make me wonder why they are RPGM games and not just renpy games.
The VN matters the most in games like these and the rpgm part just feels like unnecessary filler and makes it feel incredibly grindy. Not to forget about the bugs that fuck up your game experience.