I agree with that. I don't judge how he write. The problem I saw is, since Selebus promise to complete the harem during chapter 4, he try to make it happen, without knowing exactly how it would happen, so the story stop.
He try to figure a way to «force» the character who won't participate in depravious act (Niki, Rika, Maki, Sara, Wakana, etc...) to finally participate. The fact that Makoto propose, for the test, to being caught by her mother isn't innocent. And that's not badly done, it's quite in line with the evolution of Makoto, but I can't unsee why Selebus make her propose it now.
Sara's the same. It's not badly done... it's just... it feel like a checklist, you know?
That's why I say he shouldn't have make that promise. He should have stay on is old way, writing like a gardener (to keep your metaphor). Because, right now, it feel unatural...