The grind is mild, but it's still somewhat noticeable. However, it's somehow one of the least annoying grinds I've ever had the (dis)pleasure of encountering, to the point I actually found myself enjoying it. I'm fairly certain that's actually the intent; you really get into the feeling of just... living with your sister, going through your daily routine.
It's a good time; very relaxing, and the payoff with lewder and lewder scenes feels wonderfully rewarding.
If anything, the routine is a relatively accurate depiction of an actual Japanese salaryman's life; long working hours, leaving you with barely enough energy to get home, to the point that the Japanese have an actual term for "death by overwork." Karoshi, it's called.
In that kind of setting, your sister is a relief for you, I suppose; someone to get home to, to eat dinner with, to enjoy life with. They really captured that feeling with the 100 Days ending (you can get multiple endings per run, it's a bit like a sandbox in this sense).
Seeing as I have no clue how to use Cheat Engine, maybe my opinion in this regard is worth less; but personally speaking, I feel like the grind - that is to say, actually getting used to living with your sister, coming home and eating dinner and messing around with her (in more ways than one, hah!) is... it's part of the experience, and you'd most likely be hurting any enjoyment you might get if you just skipped over it all with Cheat Engine.
There's nothing wrong with downloading a maxed save to just bang her silly, of course, but I highly recommend that you in addition just play the game through normally at least once, for the full experience.
Overall, a wonderful game with wonderful art - lively and cute chibi sprites, attractive and tasteful CGs with very few noticeable mistakes - absolutely none of which are immersion-breaking, insofar as I could tell. I really enjoyed the monochrome colors and found myself coming back to this game from time to time even after having completed it.
Edit: If you're turned off by black and white for whatever reason, Imouto_Lover has uploaded a very nice recolor mod for the game.
Needless to say, I'm eagerly awaiting any new projects from this group. Give Imouto Life Monochrome a try; you won't regret it.