
I understand where you're coming from but many people have reclaimed queer and use it as a term for when there's not just lesbians/gay men in a story. Many queer people call queer stories what they are, queer! The people in the story don't have to specifically identify as such for it to categorized that way.
The reality of it is, while queer is a term some have deep bad history with, it's also a term taken up by many lgbtq+ people and your argument stands to feel a little rude when you call it disempowering for queer people to call a story queer. Cause it is, and trying to discredit people for calling it that may end up just invalidating what we view as a queer story. Because many gay men, lesbians (including myself) bis, pans, ace/aros, and so many more use the word queer endearingly now. No one person can speak for all of us.
Just a thought.

From my memory, the term queer has already been pretty common even when I was an early teen. While it may have had a derogatory history (but what word related to queer identities hasn't been used as a slur in the past? Gay and lesbian certainly have, because the whole existence outside cis-heteronormativity has been treated as an insult), it has arguably been reclaimed in what I personally see as a great way.
And it has filled a role of a very much needed umbrella term to encompass all us members of the community, without endlessly listing each individual label or letter. I'd argue that it's used mostly as a respectful word both within and outside of our community, to address our community as a whole or individuals, and in many cases also to identify ourselves. Not to displace other labels like gay or lesbian, but to use both alongside each other. It also includes all those among us who fall inbetween all the currently established labels of our community, those who haven't found a fitting label for themselves yet, don't wish to pick a specific label for themselves, or don't feel comfortable going into detail about it. Plus in many contexts when we use 'queer' we're able to emphasize that we mean to include everyone of our community, not just some of us.
The term queer simply has a different role from terms like lesbian, gay, bi, pan etc. When I ask for queer literature, that can include many kinds of stories, including lesbian literature. If I ask for lesbian or sapphic literature specifically, I mean exactly that. When I talk about queer experiences with my friends, we will share a different set of experiences compared to when we talk specifically about f.ex. bisexual or lesbian experiences.
If you feel like the term queer doesn't fit you, then that is entirely up to you. Noone can tell you how to identify yourself.
But based on anyone within all my queer bubbles - at home, abroad and online -, many queer advocates, and the literature that I have come across so far, I would argue that the term queer is much more widely used as a respectful term, as specified above, than as an insult, and that those who do use it as an insult would use any term related to our community in a derogatory manner regardless.
Cringing at the comments calling this a "queer" story and the characters "queer", it's so disempowering. Firstly, many still consider that word an insult, and secondly, the characters don't identity as this. They call themselves "gay" and "lesbian", the author also throws in some Japanese gay slang where her lesbian characters call themselves "bian". Ted talk over, but this really needs to be confronted, it's not respectful to those who are lesbian, gay or bisexual identified. As for the story, whilst it is progressive for it's time and place, it's sad that gay men or women went through with such marriages and sex instead of being offered the dignity to have equal marriage and have children without such "arrangements", very little drama too which seemed to be the sake of having an easy quick oneshot tbh.