Sure, if Santamagia was an enforced No-Men Yuri Paradise. But im being pendantic by trying to be technical, and so far we have no reason to believe that the Y chromosome exists in animalia at all in that universe. So if we are discussing it purely from an earth perspective, they are lesbians, but to Santamagians, physiological attraction between women would be the normal expectation.
in "Normal" definition, Cissexual is used as the opposite of transsexual, although it was done either without understanding the etymological meaning of the prefix cis- in latin, or intentional malice as the term refers someone who is heterosexual and does not experience any form of gender dysphoria. sure Cis- and Trans- are paired, opposite prefix in latin, but they are location based when related to eachother, "near/adjacent" and "far/across" not "Static" and "To Change", or in an extreme interpretation of how latin actually uses them: "Similar" vs "Different".
as for the earthlings: Daichi we lack information on, but we have no indication shes not gay. her reaction to being told she has an obligate GF now being partially skipped and the Flirty/deadpan/snarky interrupt in ch2 say shes giving Eldora a proper chance. Nana's Mom all of our information on her relationship with her spouse comes from Nana trying to politely tell her mom to fuck off and leave her depressed daughter alone.
as for Nana, i only interpret her as Luliam-sexual because we dont have enough information. Yes she bought "Im in love with the Villainess Book 1" for her tablet. As an author, i would specifically look for something much more niche to say that Nana is thinking about girls then one of the most popular domestic lesbian romance novels, especially since theyre working for YuriHime. All her other relationship thoughts so far have been a conflict between her anxiety/depression and her perception of Luliam's expectations. Shes approaching the relationship as a Demiromantic currently. in fact basically every actually well written romance story has the protagonist be a Demiromantic because they develop attraction rather then jump headlong into relationships