I don't know if I'd class any of these as gripes, but I love Kiyoko's content so much, and I know that the ability to free her was just recently added so maybe these will be addressed.
What I'd say my first gripe is, is when Kiyoko and the MC acknowledge how great it is that they can sleep together and then wake up with each other finally after freeing Kiyoko from the Astral plane. However, after sleeping together the MC is dumped outside of the house without any content to address them leaving or waking up together. I'd love to wake up and maybe having morning sex, cuddle, have breakfast together, help get the family started on their day, etc.
I'm also a little frustrated but the fact that even though they're now in the Prime Material plane instead of the Astral Plane, the MC is still treated like an outsider. Kiyoko's called the MC husband/consort, so she's acknowledged that they're spouses herself and freely tells him she loves him. I'd like to see it as though father/husband is welcomed home instead of just as a visitor passing through.
I don't know, maybe I'm playing CoC2 wrong, but dammit if Kiyoko's storyline didn't have me fall in love with her and want to be faithful to her in game, so maybe that's why I'm so frustrated by some of these things. I'd personally love content about the MC spending time and helping build up their home (not just the family size). Helping to build/refurbish the building, help with chores, learn about Kitsune culture since they're married to a Kitsune after all. Maybe even learn the Naginata and use it in combat. Learn how to cast spells from Kiyoko? I play as basically a Bard, so I personally could see a desire to learn any of those things to enhance my performances or stories. Maybe even have content where they help deal with Kiyoko's tasks for Keros and the Cherry Blossom Throne.
Another gripe I guess, is that I don't see a spot to know how many children the MCs had with Kiyoko in total. She has nine tails with my MC, so over 32 at least I believe is what the wiki states, but I know we went far past 40 at least.
I'd also wish for additional content for the MC to spend time with their other children beyond just Kinu. I know that would be a ton of work, but the Kiyoko/Kinu content really hits the family aspect home, so as a father myself, it seems very, very odd that I know next to nothing about the scores of other children beyond Kinu (I know she's the first-born and would have preferential treatment, but it just seems odd that the MC can't intentionally spend time with any of their other children, or isn't even acknowledged by them or acknowledges them personally).
Sorry, I know this is a lot and kinda moved beyond gripes in some cases, but dammit if I don't play just for Kiyoko's part of CoC2 alone.