So Canno's poly couple is rushed and doesn't quite make sense at times...well, I can't blame her. It was a tough sell. All the poly couples I know are nowhere like the one she wrote into it, and frankly at this point I doubt any couple like the one Canno wrote even exists (she's very idealistic), but she tried!
I'd just take it as her biting off more than she could chew, not in her expertise, etc. Missing the mark is a part of growing and learning. It only really hurts if she were to continue writing something that caused a significant dip in ratings long term.
Best written thing I have seen similar to a poly is in Otoyomegatari one of the women asks her husband to marry her best friend as his 2nd wife so they can be together all the time (was getting some major gay vibes there but I guess the author didn't wanna get into that for historical accuracy). The writing is, what I would consider (maybe not everyone), miles away superior and it was still a difficult sell and I much preferred the other couples/women's stories. (If anyone is curious Otoyomegatari is written with the same story structure as this except it is het and set in 19th century Central Asia).